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<!--  

 Title: Force Field Explorer</p>
 Description: Force Field Explorer Molecular Modeling Program</p>
 Copyright: Copyright (c) 2004-2025 Jay William Ponder</p>
 Institution: Jay Ponder Lab, Washington University in St. Louis</p>
 Author: Michael J. Schnieders
 Version: 25.4
 
-->
<document>
  <properties>
    <author email="ponder@dasher.wustl.edu"/>
    <title>Tinker Keywords</title>
    <meta name="Tinker Keywords"/>
  </properties>
  <body>
    <section name="Output Control">
      <subsection name="ARCHIVE" rep="CHECKBOX">Causes Tinker molecular dynamics-based programs to write trajectories
 directly to a single plain-text archive file with the .arc format. If an archive file already
 exists at the start of the calculation, then the newly generated trajectory is appended to the
 end of the existing file. The default in the absence of this keyword is to write the trajectory
 snapshots to consecutively numbered cycle files.
		</subsection>
      <subsection name="DEBUG" rep="CHECKBOX">Turns on printing of detailed information and intermediate values throughout
 the progress of a Tinker computation; not recommended for use with large structures or
 full potential energy functions since a summary of every individual interaction will usually
 be output.
		</subsection>
      <subsection name="EXIT-PAUSE" rep="CHECKBOX">This keyword causes Tinker programs to pause and wait for a carriage
 return at the end of execution prior to returning control to the operating system. This is
 useful to keep the execution window open following termination on machines running
 Microsoft Windows or Apple macOS. The default in the absence of the EXIT-PAUSE
 keyword, is to return control to the operating system immediately at program termination.
		</subsection>
      <subsection name="NOVERSION" rep="CHECKBOX">Turns off the use of version numbers appended to the end of filenames as
 the method for generating filenames for updated copies of an existing file. The presence of
 this keyword results in direct use of input file names without a search for the highest
 available version, and requires the entry of specific output file names in many additional
 cases. By default, in the absence of this keyword, Tinker generates and attaches version
 numbers to the end of file names. For example, subsequent new versions of the file molecule.xyz
 would be written first to the file molecule.xyz_2, then to molecule.xyz_3, etc.
		</subsection>
      <subsection name="OVERWRITE" rep="CHECKBOX">Causes Tinker programs, such as minimizations, that output
 intermediate coordinate sets to create a single disk file for the intermediate results which is
 successively overwritten with the new intermediate coordinates as they become available.
 This keyword is essentially the opposite of the SAVECYCLE keyword.
		</subsection>
      <subsection name="SAVE-CYCLE" rep="CHECKBOX">This keyword causes Tinker programs, such as minimizations, that
 output intermediate coordinate sets to save each successive set to the next consecutively
 numbered cycle file. The SAVE-CYCLE keyword is the opposite of the OVERWRITE
 keyword.
		</subsection>
      <subsection name="SAVE-FORCE" rep="CHECKBOX">This keyword causes Tinker molecular dynamics calculations to save the
 values of the force components on each atom to a separate cycle file. These files are written
 whenever the atomic coordinate snapshots are written during the dynamics run. Each atomic
 force file name contains as a suffix the cycle number followed by the letter f.
		</subsection>
      <subsection name="SAVE-INDUCED" rep="CHECKBOX">This keyword causes Tinker molecular dynamics calculations that
 involve polarizable atomic multipoles to save the values of the induced dipole components on
 each polarizable atom to a separate cycle file. These files are written whenever the atomic
 coordinate snapshots are written during the dynamics run. Each induced dipole file name
 contains as a suffix the cycle number followed by the letter u.
		</subsection>
      <subsection name="SAVE-VELOCITY" rep="CHECKBOX">This keyword causes Tinker molecular dynamics calculations to save
 the values of the velocity components on each atom to a separate cycle file. These files are
 written whenever the atomic coordinate snapshots are written during the dynamics run.
 Each velocity file name contains as a suffix the cycle number followed by the letter v.
		</subsection>
      <subsection name="VERBOSE" rep="CHECKBOX">Turns on printing of secondary and informational output during a variety of
 Tinker computations; a subset of the more extensive output provided by the DEBUG
 keyword.
		</subsection>
      <subsection name="DIGITS" rep="TEXTFIELD">[integer] This keyword controls the number of digits of precision output by
 Tinker in reporting potential energies and atomic coordinates. The allowed values for the
 integer modifier are 4, 6 and 8. Input values less than 4 will be set to 4, and those greater
 than 8 will be set to 8. Final energy values reported by most Tinker programs will contain
 the specified number of digits to the right of the decimal point. The number of decimal places
 to be output for atomic coordinates is generally two larger than the value of DIGITS. In the
 absence of the DIGITS keyword a default value of 4 is used, and energies will be reported to
 4 decimal places with coordinates to 6 decimal places.
		</subsection>
      <subsection name="PRINTOUT" rep="TEXTFIELD">[integer] A general parameter for iterative procedures such as
 minimizations that sets the number of iterations between writes of status information to the
 standard output. The default value in the absence of the keyword is 1, i.e., the calculation
 status is given every iteration.
		</subsection>
      <subsection name="WRITEOUT" rep="TEXTFIELD">[integer] A general parameter for iterative procedures such as
 minimizations that sets the number of iterations between writes of intermediate results
 (such as the current coordinates) to disk file(s). The default value in the absence of the
 keyword is 1, i.e., the intermediate results are written to file on every iteration. Whether
 successive results are saved to new files or replace previously written intermediate results is
 controlled by the OVERWRITE and SAVECYCLE keywords.
		</subsection>
    </section>
    <section name="Force Field Selection">
      <subsection name="FORCEFIELD" rep="TEXTFIELD">[name] This keyword provides a name for the force field to be used in the
 current calculation. Its value is usually set in the master force field parameter file for the
 calculation (see the PARAMETERS keyword) instead of in the keyfile.
		</subsection>
      <subsection name="PARAMETERS" rep="TEXTFIELD">[file name] Provides the name of the force field parameter file to be used
 for the current Tinker calculation. The standard file name extension for parameter files,
 .prm, is an optional part of the file name modifier. The default in the absence of the
 PARAMETERS keyword is to look for a parameter file with the same base name as the
 molecular system and ending in the .prm extension. If a valid parameter file is not found,
 the user will asked to provide a file name interactively.
		</subsection>
    </section>
    <section name="Potential Function Selection">
      <subsection name="ANGANGTERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the angle-angle cross term
 potential energy. In the absence of a modifying option, this keyword turns on use of the
 potential. The NONE option turns off use of this potential energy term. The ONLY option
 turns off all potential energy terms except for this one.
         <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="ANGLETERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the bond angle bending
 potential energy term. In the absence of a modifying option, this keyword turns on use of the
 potential. The NONE option turns off use of this potential energy term. The ONLY option
 turns off all potential energy terms except for this one.
        <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="BONDTERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the bond stretching potential
 energy term. In the absence of a modifying option, this keyword turns on use of the potential.
 The NONE option turns off use of this potential energy term. The ONLY option turns off all
 potential energy terms except for this one.
         <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="CHARGETERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the charge-charge
 potential energy term between pairs of atomic partial charges. In the absence of a modifying
 option, this keyword turns on use of the potential. The NONE option turns off use of this
 potential energy term. The ONLY option turns off all potential energy terms except for this
 one.
        <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="CHGDPLTERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the charge-dipole potential
 energy term between atomic partial charges and bond dipoles. In the absence of a modifying
 option, this keyword turns on use of the potential. The NONE option turns off use of this
 potential energy term. The ONLY option turns off all potential energy terms except for this
 one.
		   <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="DIPOLETERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the dipole-dipole potential
 energy term between pairs of bond dipoles. In the absence of a modifying option, this
 keyword turns on use of the potential. The NONE option turns off use of this potential
 energy term. The ONLY option turns off all potential energy terms except for this one.
		   <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="EXTRATERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the user defined extra
 potential energy term. In the absence of a modifying option, this keyword turns on use of the
 potential. The NONE option turns off use of this potential energy term. The ONLY option
 turns off all potential energy terms except for this one.
		   <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="IMPROPTERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the CHARMM-style
 improper dihedral angle potential energy term. In the absence of a modifying option, this
 keyword turns on use of the potential. The NONE option turns off use of this potential
 energy term. The ONLY option turns off all potential energy terms except for this one.
		   <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="IMPTORSTERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the AMBER-style
 improper torsional angle potential energy term. In the absence of a modifying option, this
 keyword turns on use of the potential. The NONE option turns off use of this potential
 energy term. The ONLY option turns off all potential energy terms except for this one.
		   <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="METALTERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the transition metal ligand
 field potential energy term. In the absence of a modifying option, this keyword turns on use
 of the potential. The NONE option turns off use of this potential energy term. The ONLY
 option turns off all potential energy terms except for this one. Note this keyword is present
 in the code, but not active in the current version of Tinker.
		   <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="MPOLETERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the atomic multipole
 electrostatics potential energy term. In the absence of a modifying option, this keyword turns
 on use of the potential. The NONE option turns off use of this potential energy term. The
 ONLY option turns off all potential energy terms except for this one.
		   <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="OPBENDTERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the Allinger MM-style outof-
 plane bending potential energy term. In the absence of a modifying option, this keyword
 turns on use of the potential. The NONE option turns off use of this potential energy term.
 The ONLY option turns off all potential energy terms except for this one.
		   <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="OPDISTTERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the out-of-plane distance
 potential energy term. In the absence of a modifying option, this keyword turns on use of the
 potential. The NONE option turns off use of this potential energy term. The ONLY option
 turns off all potential energy terms except for this one.
		   <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="POLARIZETERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the atomic dipole
 polarization potential energy term. In the absence of a modifying option, this keyword turns
 on use of the potential. The NONE option turns off use of this potential energy term. The
 ONLY option turns off all potential energy terms except for this one.
		   <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="RESTRAINTERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the restraint potential
 energy terms. In the absence of a modifying option, this keyword turns on use of these
 potentials. The NONE option turns off use of these potential energy terms. The ONLY option
 turns off all potential energy terms except for these terms.
		   <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="RXNFIELDTERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the reaction field
 continuum solvation potential energy term. In the absence of a modifying option, this
 keyword turns on use of the potential. The NONE option turns off use of this potential
 energy term. The ONLY option turns off all potential energy terms except for this one.
		   <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="SOLVATETERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the macroscopic solvation
 potential energy term. In the absence of a modifying option, this keyword turns on use of the
 potential. The NONE option turns off use of this potential energy term. The ONLY option
 turns off all potential energy terms except for this one.
		   <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="STRBNDTERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the bond stretching-angle
 bending cross term potential energy. In the absence of a modifying option, this keyword
 turns on use of the potential. The NONE option turns off use of this potential energy term.
 The ONLY option turns off all potential energy terms except for this one.
		   <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="STRTORTERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the bond stretchingtorsional
 angle cross term potential energy. In the absence of a modifying option, this keyword
 turns on use of the potential. The NONE option turns off use of this potential
 energy term. The ONLY option turns off all potential energy terms except for this one.
		   <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="TORSIONTERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the torsional angle
 potential energy term. In the absence of a modifying option, this keyword turns on use of the
 potential. The NONE option turns off use of this potential energy term. The ONLY option
 turns off all potential energy terms except for this one.
		   <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="TORTORTERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the torsion-torsion
 potential energy term. In the absence of a modifying option, this keyword turns on use of the
 potential. The NONE option turns off use of this potential energy term. The ONLY option
 turns off all potential energy terms except for this one. This energy term is not implemented
 in the current version of Tinker.
		   <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="UREYTERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the Urey-Bradley potential
 energy term. In the absence of a modifying option, this keyword turns on use of the potential.
 The NONE option turns off use of this potential energy term. The ONLY option turns off all
 potential energy terms except for this one.
		   <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="VDWTERM" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the van der Waals repulsiondispersion
 potential energy term. In the absence of a modifying option, this keyword turns on
 use of the potential. The NONE option turns off use of this potential energy term. The ONLY
 option turns off all potential energy terms except for this one.
		   <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
    </section>
    <section name="Potential Function Parameter">
      <subsection name="ANGANG" rep="EDITCOMBOBOX">[1 integer and 3 reals] This keyword provides the values for a single angleangle
 cross term potential parameter.
		</subsection>
      <subsection name="ANGLE" rep="EDITCOMBOBOX">[3 integers and 4 reals] This keyword provides the values for a single bond angle
 bending parameter. The integer modifiers give the atom class numbers for the three kinds of
 atoms involved in the angle which is to be defined. The real number modifiers give the force
 constant value for the angle and up to three ideal bond angles in degrees. In most cases only
 one ideal bond angle is given, and that value is used for all occurrences of the specified bond
 angle. If all three ideal angles are given, the values apply when the central atom of the angle
 is attached to 0, 1 or 2 additional hydrogen atoms, respectively. This ??????hydrogen
 environment?????? option is provided to implement the corresponding feature of Allinger???s MM
 force fields. The default units for the force constant are kcal/mole/radian2, but this can be
 controlled via the ANGLEUNIT keyword.
		</subsection>
      <subsection name="ANGLE3" rep="EDITCOMBOBOX">[3 integers and 4 reals] This keyword provides the values for a single bond angle
 bending parameter specific to atoms in 3-membered rings. The integer modifiers give the
 atom class numbers for the three kinds of atoms involved in the angle which is to be defined.
 The real number modifiers give the force constant value for the angle and up to three ideal
 bond angles in degrees. If all three ideal angles are given, the values apply when the central
 atom of the angle is attached to 0, 1 or 2 additional hydrogen atoms, respectively. The default
 units for the force constant are kcal/mole/radian2, but this can be controlled via the
 ANGLEUNIT keyword. If any ANGLE3 keywords are present, either in the master force
 field parameter file or the keyfile, then Tinker requires that special ANGLE3 parameters
 be given for all angles in 3-membered rings. In the absence of any ANGLE3 keywords,
 standard ANGLE parameters will be used for bonds in 3-membered rings.
		</subsection>
      <subsection name="ANGLE4" rep="EDITCOMBOBOX">[3 integers and 4 reals] This keyword provides the values for a single bond angle
 bending parameter specific to atoms in 4-membered rings. The integer modifiers give the
 atom class numbers for the three kinds of atoms involved in the angle which is to be defined.
 The real number modifiers give the force constant value for the angle and up to three ideal
 bond angles in degrees. If all three ideal angles are given, the values apply when the central
 atom of the angle is attached to 0, 1 or 2 additional hydrogen atoms, respectively. The default
 units for the force constant are kcal/mole/radian2, but this can be controlled via the
 ANGLEUNIT keyword. If any ANGLE4 keywords are present, either in the master force
 field parameter file or the keyfile, then Tinker requires that special ANGLE4 parameters
 be given for all angles in 4-membered rings. In the absence of any ANGLE4 keywords,
 standard ANGLE parameters will be used for bonds in 4-membered rings.
		</subsection>
      <subsection name="ANGLE5" rep="EDITCOMBOBOX">[3 integers and 4 reals] This keyword provides the values for a single bond angle
 bending parameter specific to atoms in 5-membered rings. The integer modifiers give the
 atom class numbers for the three kinds of atoms involved in the angle which is to be defined.
 The real number modifiers give the force constant value for the angle and up to three ideal
 bond angles in degrees. If all three ideal angles are given, the values apply when the central
 atom of the angle is attached to 0, 1 or 2 additional hydrogen atoms, respectively. The default
 units for the force constant are kcal/mole/radian2, but this can be controlled via the
 ANGLEUNIT keyword. If any ANGLE5 keywords are present, either in the master force
 field parameter file or the keyfile, then Tinker requires that special ANGLE5 parameters
 be given for all angles in 5-membered rings. In the absence of any ANGLE5 keywords,
 standard ANGLE parameters will be used for bonds in 5-membered rings.
		</subsection>
      <subsection name="ANGLEF" rep="EDITCOMBOBOX">[3 integers and 3 reals] This keyword provides the values for a single bond
 angle bending parameter for a SHAPES-style Fourier potential function. The integer
 modifiers give the atom class numbers for the three kinds of atoms involved in the angle
 which is to be defined. The real number modifiers give the force constant value for the angle,
 the angle shift in degrees, and the periodicity value. Note that the force constant should be
 given as the ??????harmonic?????? value and not the native Fourier value. The default units for the
 force constant are kcal/mole/radian2, but this can be controlled via the ANGLEUNIT
 keyword.
		</subsection>
      <subsection name="ATOM" rep="EDITCOMBOBOX">[2 integers, name, quoted string, integer, real and integer] This keyword
 provides the values needed to define a single force field atom type.
		</subsection>
      <subsection name="BIOTYPE" rep="EDITCOMBOBOX">[integer, name, quoted string and integer] This keyword provides the values
 to define the correspondence between a single biopolymer atom type and its force field atom
 type.
		</subsection>
      <subsection name="BOND" rep="EDITCOMBOBOX">[2 integers and 2 reals] This keyword provides the values for a single bond
 stretching parameter. The integer modifiers give the atom class numbers for the two kinds of
 atoms involved in the bond which is to be defined. The real number modifiers give the force
 constant value for the bond and the ideal bond length in ??. The default units for the force
 constant are kcal/mole/??2, but this can be controlled via the BONDUNIT keyword.
		</subsection>
      <subsection name="BOND3" rep="EDITCOMBOBOX">[2 integers and 2 reals] This keyword provides the values for a single bond
 stretching parameter specific to atoms in 3-membered rings. The integer modifiers give the
 atom class numbers for the two kinds of atoms involved in the bond which is to be defined.
 The real number modifiers give the force constant value for the bond and the ideal bond
 length in ??. The default units for the force constant are kcal/mole/??2, but this can be
 controlled via the BONDUNIT keyword. If any BOND3 keywords are present, either in the
 master force field parameter file or the keyfile, then Tinker requires that special BOND3
 parameters be given for all bonds in 3-membered rings. In the absence of any BOND3
 keywords, standard BOND parameters will be used for bonds in 3-membered rings.
		</subsection>
      <subsection name="BOND4" rep="EDITCOMBOBOX">[2 integers and 2 reals] This keyword provides the values for a single bond
 stretching parameter specific to atoms in 4-membered rings. The integer modifiers give the
 atom class numbers for the two kinds of atoms involved in the bond which is to be defined.
 The real number modifiers give the force constant value for the bond and the ideal bond
 length in ??. The default units for the force constant are kcal/mole/??2, but this can be
 controlled via the BONDUNIT keyword. If any BOND4 keywords are present, either in the
 master force field parameter file or the keyfile, then Tinker requires that special BOND4
 parameters be given for all bonds in 4-membered rings. In the absence of any BOND4
 keywords, standard BOND parameters will be used for bonds in 4-membered rings
		</subsection>
      <subsection name="BOND5" rep="EDITCOMBOBOX">[2 integers and 2 reals] This keyword provides the values for a single bond
 stretching parameter specific to atoms in 5-membered rings. The integer modifiers give the
 atom class numbers for the two kinds of atoms involved in the bond which is to be defined.
 The real number modifiers give the force constant value for the bond and the ideal bond
 length in ??. The default units for the force constant are kcal/mole/??2, but this can be
 controlled via the BONDUNIT keyword. If any BOND5 keywords are present, either in the
 master force field parameter file or the keyfile, then Tinker requires that special BOND5
 parameters be given for all bonds in 5-membered rings. In the absence of any BOND5
 keywords, standard BOND parameters will be used for bonds in 5-membered rings.
		</subsection>
      <subsection name="CHARGE" rep="EDITCOMBOBOX">[1 integer and 1 real] This keyword provides a value for a single atomic partial
 charge electrostatic parameter. The integer modifier, if positive, gives the atom type number
 for which the charge parameter is to be defined. Note that vdw parameters are given for
 atom types, not atom classes. If the integer modifier is negative, then the parameter value to
 follow applies only to the individual atom whose atom number is the negative of the modifier.
 The real number modifier gives the values of the atomic partial charge in electrons.
		</subsection>
      <subsection name="DIPOLE" rep="EDITCOMBOBOX">[2 integers and 2 reals] This keyword provides the values for a single bond
 dipole electrostatic parameter. The integer modifiers give the atom type numbers for the two
 kinds of atoms involved in the bond dipole which is to be defined. The real number modifiers
 give the value of the bond dipole in Debyes and the position of the dipole site along the bond.
 If the bond dipole value is positive, then the first of the two atom types is the positive end of
 the dipole. For a negative bond dipole value, the first atom type listed is negative. The
 position along the bond is an optional modifier that gives the postion of the dipole site as a
 fraction between the first atom type (position=0) and the second atom type (position=1). The
 default for the dipole position in the absence of a specified value is 0.5, placing the dipole at
 the midpoint of the bond.
		</subsection>
      <subsection name="DIPOLE3" rep="EDITCOMBOBOX"> [2 integers and 2 reals] This keyword provides the values for a single bond
 dipole electrostatic parameter specific to atoms in 3-membered rings. The integer modifiers
 give the atom type numbers for the two kinds of atoms involved in the bond dipole which is
 to be defined. The real number modifiers give the value of the bond dipole in Debyes and the
 position of the dipole site along the bond. The default for the dipole position in the absence of
 a specified value is 0.5, placing the dipole at the midpoint of the bond. If any DIPOLE3
 keywords are present, either in the master force field parameter file or the keyfile, then
 Tinker requires that special DIPOLE3 parameters be given for all bond dipoles in 3-
 membered rings. In the absence of any DIPOLE3 keywords, standard DIPOLE parameters
 will be used for bonds in 3-membered rings.
		</subsection>
      <subsection name="DIPOLE4" rep="EDITCOMBOBOX">[2 integers and 2 reals] This keyword provides the values for a single bond
 dipole electrostatic parameter specific to atoms in 4-membered rings. The integer modifiers
 give the atom type numbers for the two kinds of atoms involved in the bond dipole which is
 to be defined. The real number modifiers give the value of the bond dipole in Debyes and the
 position of the dipole site along the bond. The default for the dipole position in the absence of
 a specified value is 0.5, placing the dipole at the midpoint of the bond. If any DIPOLE4
 keywords are present, either in the master force field parameter file or the keyfile, then
 Tinker requires that special DIPOLE4 parameters be given for all bond dipoles in 4-
 membered rings. In the absence of any DIPOLE4 keywords, standard DIPOLE parameters
 will be used for bonds in 4-membered rings.
		</subsection>
      <subsection name="DIPOLE5" rep="EDITCOMBOBOX">[2 integers and 2 reals] This keyword provides the values for a single bond
 dipole electrostatic parameter specific to atoms in 5-membered rings. The integer modifiers
 give the atom type numbers for the two kinds of atoms involved in the bond dipole which is
 to be defined. The real number modifiers give the value of the bond dipole in Debyes and the
 position of the dipole site along the bond. The default for the dipole position in the absence of
 a specified value is 0.5, placing the dipole at the midpoint of the bond. If any DIPOLE5
 keywords are present, either in the master force field parameter file or the keyfile, then
 Tinker requires that special DIPOLE5 parameters be given for all bond dipoles in 5-
 membered rings. In the absence of any DIPOLE5 keywords, standard DIPOLE parameters
 will be used for bonds in 5-membered rings.
		</subsection>
      <subsection name="ELECTNEG" rep="EDITCOMBOBOX">[3 integers and 1 real] This keyword provides the values for a single
 electronegativity bond length correction parameter. The first two integer modifiers give the
 atom class numbers of the atoms involved in the bond to be corrected. The third integer
 modifier is the atom class of an electronegative atom. In the case of a primary correction, an
 atom of this third class must be directly bonded to an atom of the second atom class. For a
 secondary correction, the third class is one atom removed from an atom of the second class.
 The real number modifier is the value in ?? by which the original ideal bond length is to be
 corrected.
		</subsection>
      <subsection name="HBOND" rep="EDITCOMBOBOX">[2 integers and 2 reals] This keyword provides the values for the MM3-style
 directional hydrogen bonding parameters for a single pair of atoms. The integer modifiers
 give the pair of atom class numbers for which hydrogen bonding parameters are to be
 defined. The two real number modifiers give the values of the minimum energy contact
 distance in ?? and the well depth at the minimum distance in kcal/mole.
		</subsection>
      <subsection name="IMPTORS" rep="EDITCOMBOBOX">[4 integers and up to 3 real/real/integer triples] This keyword provides the
 values for a single AMBER-style improper torsional angle parameter. The first four integer
 modifiers give the atom class numbers for the atoms involved in the improper torsional angle
 to be defined. By convention, the third atom class of the four is the trigonal atom on which
 the improper torsion is centered. The torsional angle computed is literally that defined by the
 four atom classes in the order specified by the keyword. Each of the remaining triples of
 real/real/integer modifiers give the half-amplitude, phase offset in degrees and periodicity of
 a particular improper torsional term, respectively. Periodicities through 3-fold are allowed
 for improper torsional parameters.
		</subsection>
      <subsection name="OPBEND" rep="EDITCOMBOBOX">[2 integers and 1 real] This keyword provides the values for a single Allinger
 MM-style out-of-plane angle bending potential parameter. The first integer modifier is the
 atom class of the central trigonal atom and the second integer is the atom class of the out-ofplane
 atom. The real number modifier gives the force constant value for the out-of-plane
 angle. The default units for the force constant are kcal/mole/radian2, but this can be
 controlled via the OPBENDUNIT keyword.
		</subsection>
      <subsection name="OPDIST" rep="EDITCOMBOBOX">[4 integers and 1 real] This keyword provides the values for a single out-of-plane
 distance potential parameter. The first integer modifier is the atom class of the central
 trigonal atom and the three following integer modifiers are the atom classes of the three
 attached atoms. The real number modifier is the force constant for the harmonic function of
 the out-of-plane distance of the central atom. The default units for the force constant are
 kcal/mole/??2, but this can be controlled via the OPDISTUNIT keyword.
		</subsection>
      <subsection name="PIATOM" rep="EDITCOMBOBOX">[1 integer and 3 reals] This keyword provides the values for the pisystem MO
 potential parameters for a single atom class belonging to a pisystem.
		</subsection>
      <subsection name="PIBOND" rep="EDITCOMBOBOX">[2 integers and 2 reals] This keyword provides the values for the pisystem MO
 potential parameters for a single type of pisystem bond.
		</subsection>
      <subsection name="PIBOND5" rep="EDITCOMBOBOX">[2 integers and 2 reals] This keyword provides the values for the pisystem MO
 potential parameters for a single type of pisystem bond.
		</subsection>
      <subsection name="PITORS" rep="EDITCOMBOBOX">[2 integers and 1 real] This keyword provides the values for a single pi-torsion
 potential parameter. The two integer modifiers give the atom class numbers for the atoms
 involved in the central bond of the torsional angle to be parameterized. The real modifier
 gives the value of the 2-fold Fourier amplitude for the torsional angle between p-orbitals
 centered on the defined bond atom classes. The default units for the stretch-torsion force
 constant can be controlled via the PITORSUNIT keyword.
		</subsection>
      <subsection name="POLARIZE" rep="EDITCOMBOBOX">[1 integer and 1 real] This keyword provides the values for a single atomic
 dipole polarizability parameter. The integer modifier, if positive, gives the atom type number
 for which a polarizability parameter is to be defined. If the integer modifier is negative, then
 the parameter value to follow applies only to the individual atom whose atom number is the
 negative of the modifier. The real number modifier gives the value of the dipole polarizability
 in ??3.
		</subsection>
      <subsection name="STRBND" rep="EDITCOMBOBOX"> [1 integer and 3 reals] This keyword provides the values for a single stretchbend
 cross term potential parameter. The integer modifier gives the atom class number for
 the central atom of the bond angle involved in stretch-bend interactions. The real number
 modifiers give the force constant values to be used when the central atom of the angle is
 attached to 0, 1 or 2 additional hydrogen atoms, respectively. The default units for the
 stretch-bend force constant are kcal/mole/??-degree, but this can be controlled via the
 STRBNDUNIT keyword.
		</subsection>
      <subsection name="STRTORS" rep="EDITCOMBOBOX">[2 integers and 1 real] This keyword provides the values for a single stretchtorsion
 cross term potential parameter. The two integer modifiers give the atom class
 numbers for the atoms involved in the central bond of the torsional angles to be
 parameterized. The real modifier gives the value of the stretch-torsion force constant for all
 torsional angles with the defined central bond atom classes. The default units for the stretchtorsion
 force constant can be controlled via the STRTORUNIT keyword.
		</subsection>
      <subsection name="TORSION" rep="EDITCOMBOBOX">[4 integers and up to 6 real/real/integer triples] This keyword provides the
 values for a single torsional angle parameter. The first four integer modifiers give the atom
 class numbers for the atoms involved in the torsional angle to be defined. Each of the
 remaining triples of real/real/integer modifiers give the half-amplitude, phase offset in
 degrees and periodicity of a particular torsional function term, respectively. Periodicities
 through 6-fold are allowed for torsional parameters.
		</subsection>
      <subsection name="TORSION4" rep="EDITCOMBOBOX">[4 integers and up to 6 real/real/integer triples] This keyword provides the
 values for a single torsional angle parameter specific to atoms in 4-membered rings. The first
 four integer modifiers give the atom class numbers for the atoms involved in the torsional
 angle to be defined. The remaining triples of real number and integer modifiers operate as
 described above for the TORSION keyword.
		</subsection>
      <subsection name="TORSION5" rep="EDITCOMBOBOX">[4 integers and up to 6 real/real/integer triples] This keyword provides the
 values for a single torsional angle parameter specific to atoms in 5-membered rings. The first
 four integer modifiers give the atom class numbers for the atoms involved in the torsional
 angle to be defined. The remaining triples of real number and integer modifiers operate as
 described above for the TORSION keyword.
		</subsection>
      <subsection name="UREYBRAD" rep="EDITCOMBOBOX">[3 integers and 2 reals] This keyword provides the values for a single Urey-
 Bradley cross term potential parameter. The integer modifiers give the atom class numbers
 for the three kinds of atoms involved in the angle for which a Urey-Bradley term is to be
 defined. The real number modifiers give the force constant value for the term and the target
 value for the 1-3 distance in ??. The default units for the force constant are kcal/mole/??2, but
 this can be controlled via the UREYUNIT keyword.
		</subsection>
      <subsection name="VDW" rep="EDITCOMBOBOX">[1 integer and 3 reals] This keyword provides values for a single van der Waals
 parameter. The integer modifier, if positive, gives the atom class number for which vdw
 parameters are to be defined. Note that vdw parameters are given for atom classes, not atom
 types. The three real number modifiers give the values of the atom size in ??, homoatomic
 well depth in kcal/mole, and an optional reduction factor for univalent atoms.
		</subsection>
      <subsection name="VDW14" rep="EDITCOMBOBOX">[1 integer and 2 reals] This keyword provides values for a single van der Waals
 parameter for use in 1-4 nonbonded interactions. The integer modifier, if positive, gives the
 atom class number for which vdw parameters are to be defined. Note that vdw parameters
 are given for atom classes, not atom types. The two real number modifiers give the values of
 the atom size in ?? and the homoatomic well depth in kcal/mole. Reduction factors, if used,
 are carried over from the VDW keyword for the same atom class.
		</subsection>
      <subsection name="VDWPR" rep="EDITCOMBOBOX">[2 integers and 2 reals] This keyword provides the values for the vdw parameters
 for a single special heteroatomic pair of atoms. The integer modifiers give the pair of atom
 class numbers for which special vdw parameters are to be defined. The two real number
 modifiers give the values of the minimum energy contact distance in ?? and the well depth at
 the minimum distance in kcal/mole.
		</subsection>
      <subsection name="METAL" rep="EDITCOMBOBOX"> This keyword provides the values for a single transition metal ligand field
 parameter. Note this keyword is present in the code, but not active in the current
 version of Tinker.
		</subsection>
      <subsection name="SOLVATE" rep="COMBOBOX">[ASP/SASA/ONION/STILL/HCT/ACE/GBSA] Use of this keyword during
 energy calculations with any of the standard force fields turns on a continuum solvation free
 energy term. Several algorithms are available based on the modifier used: ASP= Eisenberg-
 McLachlan ASP method using the Wesson-Eisenberg vacuum-to-water parameters; SASA=
 the Ooi-Scheraga SASA method; ONION= the original 1990 Still ??????Onion-shell?????? GB/SA
 method; STILL= the 1997 analytical GB/SA method from Still???s group; HCT= the pairwise
 descreening method of Hawkins, Cramer and Truhlar; ACE= the Analytical Continuum
 Electrostatics solvation method from the Karplus group; GBSA= equivalent to the STILL
 modifier. At present, GB/SA-style methods are only valid for force fields that use simple
 partial charge electrostatics.
         <Value name="ASP"/>
        <Value name="SASA"/>
        <Value name="ONION"/>
        <Value name="STILL"/>
        <Value name="HCT"/>
        <Value name="ACE"/>
        <Value name="GBSA"/>
        <Value name="GK"/>
        <Value name="PB"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="IMPROPER" rep="COMBOBOX">[NONE/ONLY] This keyword controls use of the CHARMM-style
 improper dihedral angle potential energy term. In the absence of a modifying option, this
 keyword turns on use of the potential. The NONE option turns off use of this potential
 energy term. The ONLY option turns off all potential energy terms except for this one.
         <Value name="PRESENT"/>
        <Value name="NONE"/>
        <Value name="ONLY"/>
        <Value name="DEFAULT"/>
      </subsection>
    </section>
    <section name="Energy Unit Conversion">
      <subsection name="ANGLEUNIT" rep="TEXTFIELD">[real] Sets the scale factor needed to convert the energy value computed by
 the bond angle bending potential into units of kcal/mole. The correct value is force field
 dependent and typically provided in the header of the master force field parameter file. The
 default value of (p/180)2 = 0.0003046 is used, if the ANGLEUNIT keyword is not given in the
 force field parameter file or the keyfile.
		</subsection>
      <subsection name="ANGANGUNIT" rep="TEXTFIELD">[real] Sets the scale factor needed to convert the energy value computed
 by the angle-angle cross term potential into units of kcal/mole. The correct value is force field
 dependent and typically provided in the header of the master force field parameter file. The
 default of (p/180)2 = 0.0003046 is used, if the ANGANGUNIT keyword is not given in the
 force field parameter file or the keyfile.
		</subsection>
      <subsection name="BONDUNIT" rep="TEXTFIELD">[real] Sets the scale factor needed to convert the energy value computed by
 the bond stretching potential into units of kcal/mole. The correct value is force field
 dependent and typically provided in the header of the master force field parameter file. The
 default value of 1.0 is used, if the BONDUNIT keyword is not given in the force field
 parameter file or the keyfile.
		</subsection>
      <subsection name="IMPROPUNIT" rep="TEXTFIELD">[real] Sets the scale factor needed to convert the energy value computed
 by the CHARMM-style improper dihedral angle potential into units of kcal/mole. The correct
 value is force field dependent and typically provided in the header of the master force field
 parameter file. The default value of 1.0 is used, if the IMPROPUNIT keyword is not given in
 the force field parameter file or the keyfile.
		</subsection>
      <subsection name="IMPTORUNIT" rep="TEXTFIELD">[real] Sets the scale factor needed to convert the energy value computed
 by the AMBER-style improper torsional angle potential into units of kcal/mole. The correct
 value is force field dependent and typically provided in the header of the master force field
 parameter file. The default value of 1.0 is used, if the IMPTORSUNIT keyword is not given
 in the force field parameter file or the keyfile.
		</subsection>
      <subsection name="OPBENDUNIT" rep="TEXTFIELD">[real] Sets the scale factor needed to convert the energy value computed
 by the Allinger MM-style out-of-plane bending potential into units of kcal/mole. The correct
 value is force field dependent and typically provided in the header of the master force field
 parameter file. The default of (p/180)2 = 0.0003046 is used, if the OPBENDUNIT keyword is
 not given in the force field parameter file or the keyfile.
		</subsection>
      <subsection name="OPDISTUNIT" rep="TEXTFIELD">[real] Sets the scale factor needed to convert the energy value computed
 by the out-of-plane distance potential into units of kcal/mole. The correct value is force field
 dependent and typically provided in the header of the master force field parameter file. The
 default value of 1.0 is used, if the OPDISTUNIT keyword is not given in the force field
 parameter file or the keyfile.
		</subsection>
      <subsection name="PITORSUNIT" rep="TEXTFIELD">[real] Sets the scale factor needed to convert the energy value computed
 by the pi-torsion potential into units of kcal/mole. The correct value is force field dependent
 and typically provided in the header of the master force field parameter file. The default
 value of 1.0 is used, if the PITORSUNIT keyword is not given in the force field parameter file
 or the keyfile.
		</subsection>
      <subsection name="STRBNDUNIT" rep="TEXTFIELD">[real] Sets the scale factor needed to convert the energy value computed
 by the bond stretching-angle bending cross term potential into units of kcal/mole. The correct
 value is force field dependent and typically provided in the header of the master force field
 parameter file. The default value of 1.0 is used, if the STRBNDUNIT keyword is not given in
 the force field parameter file or the keyfile.
		</subsection>
      <subsection name="STRTORUNIT" rep="TEXTFIELD">[real] Sets the scale factor needed to convert the energy value computed
 by the bond stretching-torsional angle cross term potential into units of kcal/mole. The
 correct value is force field dependent and typically provided in the header of the master force
 field parameter file. The default value of 1.0 is used, if the STRTORUNIT keyword is not
 given in the force field parameter file or the keyfile.
		</subsection>
      <subsection name="TORSIONUNIT" rep="TEXTFIELD">[real] Sets the scale factor needed to convert the energy value computed
 by the torsional angle potential into units of kcal/mole. The correct value is force field
 dependent and typically provided in the header of the master force field parameter file. The
 default value of 1.0 is used, if the TORSIONUNIT keyword is not given in the force field
 parameter file or the keyfile.
		</subsection>
      <subsection name="TORTORUNIT" rep="TEXTFIELD">[real] Sets the scale factor needed to convert the energy value computed
 by the torsion-torsion potential into units of kcal/mole. The correct value is force field
 dependent and typically provided in the header of the master force field parameter file. The
 default value of 1.0 is used, if the TORTORUNIT keyword is not given in the force field parameter
 file or the keyfile.
		</subsection>
      <subsection name="UREYUNIT" rep="TEXTFIELD">[real] Sets the scale factor needed to convert the energy value computed by
 the Urey-Bradley potential into units of kcal/mole. The correct value is force field dependent
 and typically provided in the header of the master force field parameter file. The default
 value of 1.0 is used, if the UREYUNIT keyword is not given in the force field parameter file
 or the keyfile.
		</subsection>
    </section>
    <section name="Local Geometry Functional Form">
      <subsection name="MM2-STRBND" rep="CHECKBOX">This keyword switches the behavior of the stretch-bend potential function
 to match the formulation used by the MM2 force field. In MM2, stretching of bonds to
 attached hydrogen atoms is not including in computing the stretch-bend cross term energy.
 The default behavior in the absence of this keyword is to include stretching of attached
 hydrogen atoms as in the MM3 force field.
		</subsection>
      <subsection name="ANGLE-CUBIC" rep="TEXTFIELD">[real] Sets the value of the cubic term in the Taylor series expansion
 form of the bond angle bending potential energy. The real number modifier gives the value of
 the coefficient as a multiple of the quadratic coefficient. This term multiplied by the angle
 bending energy unit conversion factor, the force constant, and the cube of the deviation of the
 bond angle from its ideal value gives the cubic contribution to the angle bending energy. The
 default value in the absence of the ANGLE-CUBIC keyword is zero; i.e., the cubic angle
 bending term is omitted.
		</subsection>
      <subsection name="ANGLE-QUARTIC" rep="TEXTFIELD">[real] Sets the value of the quartic term in the Taylor series
 expansion form of the bond angle bending potential energy. The real number modifier gives
 the value of the coefficient as a multiple of the quadratic coefficient. This term multiplied by
 the angle bending energy unit conversion factor, the force constant, and the forth power of
 the deviation of the bond angle from its ideal value gives the quartic contribution to the
 angle bending energy. The default value in the absence of the ANGLE-QUARTIC keyword is
 zero; i.e., the quartic angle bending term is omitted.
		</subsection>
      <subsection name="ANGLE-PENTIC" rep="TEXTFIELD">[real] Sets the value of the fifth power term in the Taylor series
 expansion form of the bond angle bending potential energy. The real number modifier gives
 the value of the coefficient as a multiple of the quadratic coefficient. This term multiplied by
 the angle bending energy unit conversion factor, the force constant, and the fifth power of the
 deviation of the bond angle from its ideal value gives the pentic contribution to the angle
 bending energy. The default value in the absence of the ANGLE-PENTIC keyword is zero;
 i.e., the pentic angle bending term is omitted.
		</subsection>
      <subsection name="ANGLE-SEXTIC" rep="TEXTFIELD">[real] Sets the value of the sixth power term in the Taylor series
 expansion form of the bond angle bending potential energy. The real number modifier gives
 the value of the coefficient as a multiple of the quadratic coefficient. This term multiplied by
 the angle bending energy unit conversion factor, the force constant, and the sixth power of
 the deviation of the bond angle from its ideal value gives the sextic contribution to the angle
 bending energy. The default value in the absence of the ANGLE-SEXTIC keyword is zero;
 i.e., the sextic angle bending term is omitted.
		</subsection>
      <subsection name="BOND-CUBIC" rep="TEXTFIELD">[real] Sets the value of the cubic term in the Taylor series expansion form
 of the bond stretching potential energy. The real number modifier gives the value of the
 coefficient as a multiple of the quadratic coefficient. This term multiplied by the bond
 stretching energy unit conversion factor, the force constant, and the cube of the deviation of
 the bond length from its ideal value gives the cubic contribution to the bond stretching
 energy. The default value in the absence of the BOND-CUBIC keyword is zero; i.e., the cubic
 bond stretching term is omitted.
		</subsection>
      <subsection name="BOND-QUARTIC" rep="TEXTFIELD">[real] Sets the value of the quartic term in the Taylor series expansion
 form of the bond stretching potential energy. The real number modifier gives the value of the
 coefficient as a multiple of the quadratic coefficient. This term multiplied by the bond
 stretching energy unit conversion factor, the force constant, and the forth power of the
 deviation of the bond length from its ideal value gives the quartic contribution to the bond
 stretching energy. The default value in the absence of the BOND-QUARTIC keyword is zero;
 i.e., the quartic bond stretching term is omitted.
		</subsection>
      <subsection name="BONDTYPE" rep="COMBOBOX">[TAYLOR/MORSE/GAUSSIAN] Chooses the functional form of the bond
 stretching potential. The TAYLOR option selects a Taylor series expansion containing terms
 from harmonic through quartic. The MORSE option selects a Morse potential fit to the ideal
 bond length and stretching force constant parameter values. The GAUSSIAN option uses an
 inverted Gaussian with amplitude equal to the Morse bond dissociation energy and width set
 to reproduce the vibrational frequency of a harmonic potential. The default is to use the
 TAYLOR potential.
 <Value name="TAYLOR"/>
        <Value name="MORSE"/>
        <Value name="GAUSSIAN"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="PISYSTEM" rep="TEXTFIELD">[integer list] This keyword sets the atoms within a molecule that are part of
 a conjugated p-system. The keyword is followed on the same line by a list of atom numbers
 and/or atom ranges that constitute the p-system. The Allinger MM force fields use this
 information to set up an MO calculation used to scale bond and torsion parameters involving
 p-system atoms.
		</subsection>
      <subsection name="UREY-CUBIC" rep="TEXTFIELD"> [real] Sets the value of the cubic term in the Taylor series expansion form
 of the Urey-Bradley potential energy. The real number modifier gives the value of the
 coefficient as a multiple of the quadratic coefficient. The default value in the absence of the
 UREY-CUBIC keyword is zero; i.e., the cubic Urey-Bradley term is omitted.
		</subsection>
      <subsection name="UREY-QUARTIC" rep="TEXTFIELD">[real] Sets the value of the quartic term in the Taylor series expansion
 form of the Urey-Bradley potential energy. The real number modifier gives the value of the
 coefficient as a multiple of the quadratic coefficient. The default value in the absence of the
 UREY-QUARTIC keyword is zero; i.e., the quartic Urey-Bradley term is omitted.
		</subsection>
    </section>
    <section name="Van Der Waals Functional Form">
      <subsection name="A-EXPTERM" rep="TEXTFIELD">[real] Sets the value of the premultiplier term in the Buckingham van
 der Waals function, i.e., the value of A in the formula Evdw = e { A exp[-B(Ro/R)] - C (Ro/R)^6 }.
		</subsection>
      <subsection name="B-EXPTERM" rep="TEXTFIELD">[real] Sets the value of the exponential factor in the Buckingham van
 der Waals function, i.e., the value of B in the formula Evdw = e { A exp[-B(Ro/R)] - C (Ro/R)^6 }.
		</subsection>
      <subsection name="C-EXPTERM" rep="TEXTFIELD">[real] Sets the value of the dispersion multiplier in the Buckingham
 van der Waals function, i.e., the value of C in the formula Evdw = e { A exp[-B(Ro/R)] - C
 (Ro/R)^6 }.
		</subsection>
      <subsection name="DELTA-HALGREN" rep="TEXTFIELD"> [real] Sets the value of the delta parameter in Halgren's buffered 14-7
 vdw potential energy functional form. In the absence of the DELTA-HALGREN keyword, a
 default value of 0.07 is used.
		</subsection>
      <subsection name="EPSILONRULE" rep="COMBOBOX">[GEOMETRIC/ARITHMETIC/HARMONIC/HHG] This keyword
 selects the combining rule used to derive the e value for van der Waals interactions. The
 default in the absence of the EPSILONRULE keyword is to use the GEOMETRIC mean of
 the individual espsilon values of the two atoms involved in the van der Waals interaction.
		   <Value name="GEOMETRIC"/>
        <Value name="ARITHMETIC"/>
        <Value name="HARMONIC"/>
        <Value name="HHG"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="GAMMA-HALGREN" rep="TEXTFIELD">[real] Sets the value of the gamma  parameter in Halgren's buffered 14-7
 vdw potential energy functional form. In the absence of the DELTA-HALGREN keyword, a
 default value of 0.12 is used.
		</subsection>
      <subsection name="GAUSSTYPE" rep="COMBOBOX">[LJ-2/LJ-4/MM2-2/MM3-2/IN-PLACE] This keyword specifies the underlying vdw
 form that a Gaussian vdw approximation will attempt to fit. The number of terms to be used in
 a Gaussian approximation of the Lennard-Jones van der Waals potential. The text modifier
 gives the name of the functional form to be used. Thus LJ-2 as a modifier will result in
 a 2-Gaussian fit to a Lennard-Jones vdw potential. The GAUSSTYPE keyword only takes effect
 when VDWTYPE is set to GAUSSIAN. This keyword has no default value.

		   <Value name="LJ-2"/>
        <Value name="LJ-4"/>
        <Value name="MM2-2"/>
        <Value name="MM3-2"/>
        <Value name="IN-PLACE"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="RADIUSRULE" rep="COMBOBOX">[ARITHMETIC/GEOMETRIC/CUBIC-MEAN] Sets the functional form
 of the radius combining rule for heteroatomic van der Waals potential energy interactions.
 The default in the absence of the RADIUSRULE keyword is to use the arithmetic mean
 combining rule to get radii for heteroatomic interactions.
		   <Value name="ARITHMETIC"/>
        <Value name="GEOMETRIC"/>
        <Value name="CUBIC-MEAN"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="RADIUSSIZE" rep="COMBOBOX">[RADIUS/DIAMETER] Determines whether the atom size values given
 in van der Waals parameters read from VDW keyword statements are interpreted as atomic
 radius or diameter values. The default in the absence of the RADIUSSIZE keyword is to
 assume that vdw size parameters are given as radius values.
		   <Value name="RADIUS"/>
        <Value name="DIAMETER"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="RADIUSTYPE" rep="COMBOBOX">[R-MIN/SIGMA] Determines whether atom size values given in van der
 Waals parameters read from VDW keyword statements are interpreted as potential
 minimum (Rmin) or LJ-style sigma (s) values. The default in the absence of the
 RADIUSTYPE keyword is to assume that vdw size parameters are given as Rmin values.
		   <Value name="R-MIN"/>
        <Value name="SIGMA"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="VDW-12-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is applied
 to van der Waals potential interactions between 1-2 connected atoms, i.e., atoms that are
 directly bonded. The default value of 0.0 is used, if the VDW-12-SCALE keyword is not given
 in either the parameter file or the keyfile.
		</subsection>
      <subsection name="VDW-13-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is applied
 to van der Waals potential interactions between 1-3 connected atoms, i.e., atoms separated
 by two covalent bonds. The default value of 0.0 is used, if the VDW-13-SCALE keyword is not
 given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="VDW-14-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is applied
 to van der Waals potential interactions between 1-4 connected atoms, i.e., atoms separated
 by three covalent bonds. The default value of 1.0 is used, if the VDW-14-SCALE keyword is
 not given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="VDW-15-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is applied
 to van der Waals potential interactions between 1-5 connected atoms, i.e., atoms separated
 by three covalent bonds. The default value of 1.0 is used, if the VDW-14-SCALE keyword is
 not given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="VDWTYPE" rep="COMBOBOX">[LENNARD-JONES/BUCKINGHAM/BUFFERED-14-7/MM3-HBOND/GAUSSIAN]
 Sets the functional form for the van der Waals potential energy term. The text modifier
 gives the name of the functional form to be used. The GAUSSIAN modifier value implements a two or four
 Gaussian fit to the corresponding Lennard-Jones function for use with potential energy smoothing schemes.
 The default in the absence of the VDWTYPE keyword is to use the standard two parameter Lennard-Jones
 function.
		   <Value name="LENNARD-JONES"/>
        <Value name="BUCKINGHAM"/>
        <Value name="BUFFERED-14-7"/>
        <Value name="MM3-HBOND"/>
        <Value name="GAUSSIAN"/>
        <Value name="DEFAULT"/>
      </subsection>
    </section>
    <section name="Electrostatics Functional Form">
      <subsection name="CHG-12-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is applied
 to charge-charge electrostatic interactions between 1-2 connected atoms, i.e., atoms that are
 directly bonded. The default value of 0.0 is used, if the CHG-12-SCALE keyword is not given
 in either the parameter file or the keyfile.
		</subsection>
      <subsection name="CHG-13-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is applied
 to charge-charge electrostatic interactions between 1-3 connected atoms, i.e., atoms
 separated by two covalent bonds. The default value of 0.0 is used, if the CHG-13-SCALE
 keyword is not given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="CHG-14-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is applied
 to charge-charge electrostatic interactions between 1-4 connected atoms, i.e., atoms
 separated by three covalent bonds. The default value of 1.0 is used, if the CHG-14-SCALE
 keyword is not given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="CHG-15-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is applied
 to charge-charge electrostatic interactions between 1-5 connected atoms, i.e., atoms
 separated by four covalent bonds. The default value of 1.0 is used, if the CHG-15-SCALE
 keyword is not given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="DIELECTRIC" rep="TEXTFIELD">[real] Sets the value of the bulk dielectric constant used to damp all
 electrostatic interaction energies for any of the Tinker electrostatic potential functions.
 The default value is force field dependent, but is usually equal to 1.0 (for Allinger's MM force
 fields the default is 1.5).
		</subsection>
      <subsection name="DIRECT-11-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is
 applied to the permanent (direct) field due to atoms within a polarization group during an
 induced dipole calculation, i.e., atoms that are in the same polarization group as the atom
 being polarized. The default value of 0.0 is used, if the DIRECT-11-SCALE keyword is not
 given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="DIRECT-12-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is
 applied to the permanent (direct) field due to atoms in 1-2 polarization groups during an
 induced dipole calculation, i.e., atoms that are in polarization groups directly connected to
 the group containing the atom being polarized. The default value of 0.0 is used, if the
 DIRECT-12-SCALE keyword is not given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="DIRECT-13-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is
 applied to the permanent (direct) field due to atoms in 1-3 polarization groups during an
 induced dipole calculation, i.e., atoms that are in polarization groups separated by one group
 from the group containing the atom being polarized. The default value of 0.0 is used, if the
 DIRECT-13-SCALE keyword is not given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="DIRECT-14-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is
 applied to the permanent (direct) field due to atoms in 1-4 polarization groups during an
 induced dipole calculation, i.e., atoms that are in polarization groups separated by two
 groups from the group containing the atom being polarized. The default value of 1.0 is used,
 if the DIRECT-14-SCALE keyword is not given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="MPOLE-12-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is
 applied to permanent atomic multipole electrostatic interactions between 1-2 connected
 atoms, i.e., atoms that are directly bonded. The default value of 0.0 is used, if the MPOLE-
 12-SCALE keyword is not given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="MPOLE-13-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is
 applied to permanent atomic multipole electrostatic interactions between 1-3 connected
 atoms, i.e., atoms that are directly bonded. The default value of 0.0 is used, if the MPOLE-
 13-SCALE keyword is not given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="MPOLE-14-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is
 applied to permanent atomic multipole electrostatic interactions between 1-4 connected
 atoms, i.e., atoms that are directly bonded. The default value of 0.0 is used, if the MPOLE-
 14-SCALE keyword is not given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="MPOLE-15-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is
 applied to permanent atomic multipole electrostatic interactions between 1-5 connected
 atoms, i.e., atoms that are directly bonded. The default value of 0.0 is used, if the MPOLE-
 15-SCALE keyword is not given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="MUTUAL-11-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is
 applied to the induced (mutual) field due to atoms within a polarization group during an
 induced dipole calculation, i.e., atoms that are in the same polarization group as the atom
 being polarized. The default value of 1.0 is used, if the MUTUAL-11-SCALE keyword is not
 given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="MUTUAL-12-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is
 applied to the induced (mutual) field due to atoms in 1-2 polarization groups during an
 induced dipole calculation, i.e., atoms that are in polarization groups directly connected to
 the group containing the atom being polarized. The default value of 1.0 is used, if the
 MUTUAL-12-SCALE keyword is not given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="MUTUAL-13-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is
 applied to the induced (mutual) field due to atoms in 1-3 polarization groups during an
 induced dipole calculation, i.e., atoms that are in polarization groups separated by one group
 from the group containing the atom being polarized. The default value of 1.0 is used, if the
 MUTUAL-13-SCALE keyword is not given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="MUTUAL-14-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is
 applied to the induced (mutual) field due to atoms in 1-4 polarization groups during an
 induced dipole calculation, i.e., atoms that are in polarization groups separated by two
 groups from the group containing the atom being polarized. The default value of 1.0 is used,
 if the MUTUAL-14-SCALE keyword is not given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="POLAR-11-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is
 applied to polarization interactions within a polarization group, i.e., pairs of atoms that are
 in the same polarization group. The default value of 0.0 is used, if the POLAR-11-SCALE
 keyword is not given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="POLAR-12-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is
 applied to polarization interactions within a polarization group, i.e., pairs of atoms that are
 in the same polarization group. The default value of 0.0 is used, if the POLAR-12-SCALE
 keyword is not given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="POLAR-13-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is
 applied to polarization interactions within a polarization group, i.e., pairs of atoms that are
 in the same polarization group. The default value of 0.0 is used, if the POLAR-13-SCALE
 keyword is not given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="POLAR-14-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is
 applied to polarization interactions within a polarization group, i.e., pairs of atoms that are
 in the same polarization group. The default value of 0.0 is used, if the POLAR-14-SCALE
 keyword is not given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="POLAR-15-SCALE" rep="TEXTFIELD">[real] This keyword provides a multiplicative scale factor that is
 applied to polarization interactions within a polarization group, i.e., pairs of atoms that are
 in the same polarization group. The default value of 0.0 is used, if the POLAR-15-SCALE
 keyword is not given in either the parameter file or the keyfile.
		</subsection>
      <subsection name="POLAR-DAMP" rep="TEXTFIELD">[2 reals] Controls the strength of the damping function applied to
 induced dipoles and dipole polarization interaction energies. The first modifier sets the
 radius in Angstoms of a hypothetical atom with unit polarizability, while the second modifier
 sets the scale factor for the exponent of the damping function. The default values for the
 radius and the scale factor are 1.662 and 1.0, respectively. Damping is eliminated entirely by
 using this keyword to set the radius value to zero.
		</subsection>
      <subsection name="POLAR-EPS" rep="TEXTFIELD">[real] This keyword sets the convergence criterion applied during
 computation of self-consistent induced dipoles. The calculation is deemed to have converged
 when the rms change (in Debyes) of the induced dipoles at all polarizable sites is less than
 the value specified with this keyword. The default value in the absence of the keyword is 10-6
 Debyes.
		</subsection>
      <subsection name="POLAR-SOR" rep="TEXTFIELD">[real] Sets a successive overrelaxation (SOR) factor for use in computation
 of induced atomic dipoles. Optimal values for this keyword will speed the induced dipole
 calculation, and poor values can result in convergence failure. The default value in the
 absence of the POLAR-SOR keyword is 0.7 which often a reasonable value when short-range
 intramolecular polarization is present. For models lacking intramolecular polarization,
 keyword values closer to 1.0 may be optimal.
		</subsection>
      <subsection name="POLARIZATION" rep="COMBOBOX">[DIRECT/MUTUAL] Selects between the use of direct and mutual
 dipole polarization for force fields that incorporate the polarization term. The DIRECT
 modifier avoids an iterative calculation by using only the permanent electric field in
 computation of induced dipoles. The MUTUAL option, which is the default in the absence of
 the POLARIZATION keyword, iterates the induced dipoles to self-consistency.
		   <Value name="DIRECT"/>
        <Value name="MUTUAL"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="REACTIONFIELD" rep="TEXTFIELD">[2 reals and 1 integer] This keyword provides parameters needed for
 the reaction field potential energy calculation. The two real modifiers give the radius of the
 dielectric cavity and the ratio of the bulk dielectric outside the cavity to that inside the
 cavity. The integer modifier gives the number of terms in the reaction field summation to be
 used. In the absence of the REACTIONFIELD keyword, the default values are a cavity of
 radius 1000000 ??, a dielectric ratio of 80 and use of only the first term of the reaction field
 summation.
		</subsection>
      <subsection name="POLAR-OLD" rep="CHECKBOX">This keyword selects the polarization damping scheme used in Tinker 3.8
 and earlier. Beginning with the 3.9 release, Tinker implements a short range polarization
 damping method due to Thole. This option is included primarily to allow continued use of the
 early Tinker polarizable water model based on the originally implemented flat
 multiplicative damping.
		</subsection>
    </section>
    <section name="Nonbonded Cutoff Keywords">
      <subsection name="CHG-CUTOFF" rep="TEXTFIELD">[real] Sets the cutoff distance value in Angstroms for charge-charge
 electrostatic potential energy interactions. The energy for any pair of sites beyond the cutoff
 distance will be set to zero. Other keywords can be used to select a smoothing scheme near
 the cutoff distance. The default cutoff distance in the absence of the CHG-CUTOFF keyword
 is infinite for nonperiodic systems and 9.0 for periodic systems.
		</subsection>
      <subsection name="CHG-TAPER" rep="TEXTFIELD">[real] This keyword allows modification of the cutoff window for chargecharge
 electrostatic potential energy interactions. It is similar in form and action to the
 TAPER keyword, except that its value applies only to the charge-charge potential. The
 default value in the absence of the CHG-TAPER keyword is to begin the cutoff window at
 0.65 of the corresponding cutoff distance.
		</subsection>
      <subsection name="CUTOFF" rep="TEXTFIELD">[real] Sets the cutoff distance value for all nonbonded potential energy
 interactions. The energy for any of the nonbonded potentials of a pair of sites beyond the
 cutoff distance will be set to zero. Other keywords can be used to select a smoothing scheme
 near the cutoff distance, or to apply different cutoff distances to various nonbonded energy
 terms.
		</subsection>
      <subsection name="DPL-CUTOFF" rep="TEXTFIELD">[real] Sets the cutoff distance value in Angstroms for bond dipole-bond
 dipole electrostatic potential energy interactions. The energy for any pair of bond dipole sites
 beyond the cutoff distance will be set to zero. Other keywords can be used to select a
 smoothing scheme near the cutoff distance. The default cutoff distance in the absence of the
 DPL-CUTOFF keyword is essentially infinite for nonperiodic systems and 10.0 for periodic
 systems.
		</subsection>
      <subsection name="DPL-TAPER" rep="TEXTFIELD">[real] This keyword allows modification of the cutoff windows for bond
 dipole-bond dipole electrostatic potential energy interactions. It is similar in form and action
 to the TAPER keyword, except that its value applies only to the vdw potential. The default
 value in the absence of the DPL-TAPER keyword is to begin the cutoff window at 0.75 of the
 dipole cutoff distance.
		</subsection>
      <subsection name="HESS-CUTOFF" rep="TEXTFIELD">[real] This keyword defines a lower limit for significant Hessian matrix
 elements. During computation of the Hessian matrix of partial second derivatives, any
 matrix elements with absolute value below HESS-CUTOFF will be set to zero and omitted
 from the sparse matrix Hessian storage scheme used by Tinker. For most calculations, the
 default in the absence of this keyword is zero, i.e., all elements will be stored. For most
 Truncated Newton optimizations the Hessian cutoff will be chosen dynamically by the
 optimizer.
		</subsection>
      <subsection name="MPOLE-CUTOFF" rep="TEXTFIELD">[real] Sets the cutoff distance value in Angstroms for atomic
 multipole potential energy interactions. The energy for any pair of sites beyond the cutoff
 distance will be set to zero. Other keywords can be used to select a smoothing scheme near
 the cutoff distance. The default cutoff distance in the absence of the MPOLE-CUTOFF
 keyword is infinite for nonperiodic systems and 9.0 for periodic systems.
		</subsection>
      <subsection name="MPOLE-TAPER" rep="TEXTFIELD">[real] This keyword allows modification of the cutoff window for atomic
 multipole potential energy interactions. It is similar in form and action to the TAPER
 keyword, except that its value applies only to the atomic multipole potential. The default
 value in the absence of the MPOLE-TAPER keyword is to begin the cutoff window at 0.65 of
 the corresponding cutoff distance.
		</subsection>
      <subsection name="POLYMER-CUTOFF" rep="TEXTFIELD">[real] Sets the value of an additional cutoff parameter needed for
 infinite polymer systems. This value must be set to less than half the minimal periodic box
 dimension and should be greater than the largest possible interatomic distance that can be
 subject to scaling or exclusion as a local electrostatic or van der Waals interaction. The
 default in the absence of the POLYMER-CUTOFF keyword is 5.5 Angstroms.
		</subsection>
      <subsection name="TAPER" rep="TEXTFIELD">[real] This keyword allows modification of the cutoff windows for nonbonded
 potential energy interactions. The nonbonded terms are smoothly reduced from their
 standard value at the beginning of the cutoff window to zero at the far end of the window.
 The far end of the window is specified via the CUTOFF keyword or its potential function
 specific variants. The modifier value supplied with the TAPER keyword sets the beginning of
 the cutoff window. The modifier can be given either as an absolute distance value in
 Angstroms, or as a fraction between zero and one of the CUTOFF distance. The default value
 in the absence of the TAPER keyword ranges from 0.65 to 0.9 of the CUTOFF distance
 depending on the type of potential function. The windows are implemented via polynomialbased
 switching functions, in some cases combined with energy shifting.
		</subsection>
      <subsection name="VDW-CUTOFF" rep="TEXTFIELD">[real] Sets the cutoff distance value in Angstroms for van der Waals
 potential energy interactions. The energy for any pair of van der Waals sites beyond the
 cutoff distance will be set to zero. Other keywords can be used to select a smoothing scheme
 near the cutoff distance. The default cutoff distance in the absence of the VDW-CUTOFF
 keyword is infinite for nonperiodic systems and 9.0 for periodic systems.
		</subsection>
      <subsection name="VDW-TAPER" rep="TEXTFIELD">[real] This keyword allows modification of the cutoff windows for van der
 Waals potential energy interactions. It is similar in form and action to the TAPER keyword,
 except that its value applies only to the vdw potential. The default value in the absence of
 the VDW-TAPER keyword is to begin the cutoff window at 0.9 of the vdw cutoff distance.
		</subsection>
      <subsection name="LIGHTS" rep="CHECKBOX">This keyword turns on Method of Lights neighbor generation for the chargecharge
 potential and any of the van der Waals potentials. This method will yield identical
 energetic results to the standard double loop method. Method of Lights will be faster when
 the volume of a sphere with radius equal to the nonbond cutoff distance is significantly less
 than half the volume of the total system (i.e., the full molecular system, the crystal unit cell
 or the periodic box).
		</subsection>
      <subsection name="NEIGHBOR-GROUPS" rep="CHECKBOX">This keyword causes the attached atom to be used in determining
 the charge-charge neighbor distance for all monovalent atoms in the molecular system. Its
 use causes all monovalent atoms to be treated the same as their attached atoms for purposes
 of including or scaling 1-2, 1-3 and 1-4 interactions. This option works only for the simple
 charge-charge electrostatic potential; it does not affect bond dipole or atomic multipole
 potentials. The NEIGHBOR-GROUPS scheme is similar to that used by some common force
 fields such as ENCAD.
		</subsection>
      <subsection name="NEUTRAL-GROUPS" rep="CHECKBOX">The keyword causes the attached atom to be used in determining
 the charge-charge interaction cutoff distance for all monovalent atoms in the molecular
 system. Its use reduces cutoff discontinuities by avoiding splitting many of the largest charge
 separations found in typical molecules. Note that this keyword does not rigorously
 implement the usual concept of a neutral group as used in the literature with
 AMBER/OPLS and other force fields. This option works only for the simple charge-charge
 electrostatic potential; it does not affect bond dipole or atomic multipole potentials.
		</subsection>
      <subsection name="TRUNCATE" rep="CHECKBOX">Causes all distance-based nonbond energy cutoffs to be sharply truncated to
 an energy of zero at distances greater than the value set by the cutoff keyword(s) without use
 of any shifting, switching or smoothing schemes. At all distances within the cutoff sphere,
 the full interaction energy is computed.
		</subsection>
    </section>
    <section name="Ewald Summation">
      <subsection name="EWALD-ALPHA" rep="TEXTFIELD">[real] Sets the value of the Ewald coefficient which controls the width
 of the Gaussian screening charges during particle mesh Ewald summation. In the absence of
 the EWALD-ALPHA keyword, a value is chosen which causes interactions outside the realspace
 cutoff to be below a fixed tolerance. For most standard applications of Ewald
 summation, the program default should be used.
		</subsection>
      <subsection name="EWALD-CUTOFF" rep="TEXTFIELD">[real] Sets the value in Angstroms of the real-space distance cutoff for
 use during Ewald summation. By default, in the absence of the EWALD-CUTOFF keyword,
 a value of 9.0 is used.
		</subsection>
      <subsection name="EWALD-FRACTION" rep="TEXTFIELD">[real] Sets the fraction between 0 and 1 of reciprocal space included
 in the reciprocal sum when using regular Ewald summation. The keyword has no effect on
 PME calculations. A default value of 0.216 is used in the absence of the EWALD-FRACTION
 keyword.
		</subsection>
      <subsection name="PME-GRID" rep="TEXTFIELD">[3 integers] This keyword sets the dimensions of the charge grid used
 during particle mesh Ewald summation. The three modifiers give the size along the X-, Y-
 and Z-axes, respectively. If either the Y- or Z-axis dimensions are omitted, then they are set
 equal to the X-axis dimension. The default in the absence of the PME-GRID keyword is to set
 the grid size along each axis to the smallest power of 2, 3 and/or 5 which is at least as large
 as 1.5 times the axis length in Angstoms. Note that the FFT used by PME is not restricted
 to, but is most efficient for, grid sizes which are powers of 2, 3 and/or 5.
		</subsection>
      <subsection name="PME-ORDER" rep="TEXTFIELD"> [integer] This keyword sets the order of the B-spline interpolation used
 during particle mesh Ewald summation. A default value of 8 is used in the absence of the
 PME-ORDER keyword.
		</subsection>
      <subsection name="EWALD" rep="CHECKBOX">This keyword turns on the use of Ewald summation during computation of
 electrostatic interactions in periodic systems. In the current version of Tinker, regular
 Ewald is used for polarizable atomic multipoles, and smooth particle mesh Ewald (PME) is
 used for charge-charge interactions. Ewald summation is not available for interactions
 involving bond-centered dipoles. By default, in the absence of the EWALD keyword, distancebased
 cutoffs are used for electrostatic interactions.
		</subsection>
      <subsection name="EWALD-BOUNDARY" rep="CHECKBOX">This keyword invokes the use of vacuum boundary conditions
 during Ewald summation, corresponding to the media surrounding the system having a
 dielectric value of 1. The default in the absence of the EWALD-BOUNDARY keyword is to
 use tinfoil boundary conditions where the surrounding media is assumed to have an
 infinite dielectric value.
		</subsection>
    </section>
    <section name="Crystal Lattice And Periodic Boundary">
      <subsection name="A-AXIS" rep="TEXTFIELD">[real] Sets the value of the a-axis length for a crystal unit cell, or, equivalently,
 the X-axis length for a periodic box. The length value in Angstroms is listed after the
 keyword.
		</subsection>
      <subsection name="B-AXIS" rep="TEXTFIELD">[real] Sets the value of the b-axis length for a crystal unit cell, or, equivalently,
 the Y-axis length for a periodic box. The length value in Angstroms is listed after the
 keyword.
		</subsection>
      <subsection name="C-AXIS" rep="TEXTFIELD">[real] Sets the value of the C-axis length for a crystal unit cell, or, equivalently,
 the Z-axis length for a periodic box. The length value in Angstroms is listed after the
 keyword. If the keyword is DEFAULT, the C-axis length is set equal to the A-axis length.
		</subsection>
      <subsection name="ALPHA" rep="TEXTFIELD">[real] Sets the value of the ?? angle of a crystal unit cell, i.e., the angle between
 the b-axis and c-axis of a unit cell, or, equivalently, the angle between the Y-axis and Z-axis
 of a periodic box. The default value in the absence of the ALPHA keyword is 90 degrees.
		</subsection>
      <subsection name="BETA" rep="TEXTFIELD">[real] Sets the value of the ?? angle of a crystal unit cell, i.e., the angle between the
 a-axis and c-axis of a unit cell, or, equivalently, the angle between the X-axis and Z-axis of a
 periodic box. The default value in the absence of the BETA keyword is to set the ?? angle
 equal to the a angle as given by the keyword ALPHA.
		</subsection>
      <subsection name="GAMMA" rep="TEXTFIELD">[real] Sets the value of the gamma angle of a crystal unit cell, i.e., the angle between
 the a-axis and b-axis of a unit cell, or, equivalently, the angle between the X-axis and Z-axis
 of a periodic box. The default value in the absence of the GAMMA keyword is to set the ?
 angle equal to the a angle as given by the keyword ALPHA.
		</subsection>
      <subsection name="SPACEGROUP" rep="COMBOBOX">[name] This keyword selects the space group to be used in manipulation of crystal unit
 cells and asymmetric units. The name option must be chosen from one of the following currently
 implemented space groups: P1, P1(-), P21, Cc, P21/a, P21/n, P21/c, C2/c, P212121, Pna21, Pn21a, Cmc21,
 Pccn, Pbcn, Pbca, P41, I41/a, P4(-)21c, P4(-)m2, R3c, P7.1)/mcm, Fm3(-)m, Im3(-)m.
		<Value name="P1"/>
        <Value name="P1(-)"/>
        <Value name="P21"/>
        <Value name="Cc"/>
        <Value name="P21/a"/>
        <Value name="P21/n"/>
        <Value name="P21/c"/>
        <Value name="C2/c"/>
        <Value name="P212121"/>
        <Value name="Pna21"/>
        <Value name="Pn21a"/>
        <Value name="Cmc21"/>
        <Value name="Pccn"/>
        <Value name="Pbcn"/>
        <Value name="Pbca"/>
        <Value name="P41"/>
        <Value name="I41/a"/>
        <Value name="P4(-)21c"/>
        <Value name="P4(-)m2"/>
        <Value name="R3c"/>
        <Value name="P7.1)/mcm"/>
        <Value name="Fm3(-)m"/>
        <Value name="Im3(-)m"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="OCTAHEDRON" rep="CHECKBOX">Specifies that the periodic box is a truncated octahedron with maximal
 distance across the truncated octahedron as given by the A-AXIS keyword. All other unit cell
 and periodic box size-defining keywords are ignored if the OCTAHEDRON keyword is
 present.
		</subsection>
    </section>
    <section name="Optimization">
      <subsection name="ANGMAX" rep="TEXTFIELD">[real] Set the maximum permissible angle between the current optimization
 search direction and the negative of the gradient direction. If this maximum angle value is
 exceeded, the optimization routine will note an error condition and may restart from the
 steepest descent direction. The default value in the absence of the ANGMAX keyword is
 usually 88 degrees for conjugate gradient methods and 180 degrees (i.e., disabled) for
 variable metric optimizations.
		</subsection>
      <subsection name="CAPPA" rep="TEXTFIELD">[real] This keyword is used to set the normal termination criterion for the line
 search phase of Tinker optimization routines. The line search exits successfully if the ratio
 of the current gradient projection on the line to the projection at the start of the line search
 falls below the value of CAPPA. A default value of 0.1 is used in the absence of the CAPPA
 keyword.
		</subsection>
      <subsection name="FCTMIN" rep="TEXTFIELD">[real] This keyword sets a convergence criterion for successful completion of a
 Tinker optimization. If the value of the optimization objective function, typically the
 potential energy, falls below the value set by FCTMIN, then the optimization is deemed to
 have converged. The default value in the absence of the FCTMIN keyword is -1000000,
 effectively removing this criterion as a possible agent for termination.
		</subsection>
      <subsection name="HGUESS" rep="TEXTFIELD">[real] Sets an initial guess for the average value of the diagonal elements of the
 scaled inverse Hessian matrix used by the optimally conditioned variable metric
 optimization routine. A default value of 0.4 is used in the absence of the HGUESS keyword.
 IMPROPER [4 integers and 2 reals] This keyword provides the values for a single
 CHARMM-style improper dihedral angle parameter.
		</subsection>
      <subsection name="INTMAX" rep="TEXTFIELD">[integer] Sets the maximum number of interpolation cycles that will be allowed
 during the line search phase of an optimization. All gradient-based Tinker optimization
 routines use a common line search routine involving quadratic extrapolation and cubic
 interpolation. If the value ofMAX is reached, an error status is set for the line search
 and the search is repeated with a much smaller initial step size. The default value in the
 absence of this keyword is optimization routine dependent, but is usually in the range 5 to
 10.
		</subsection>
      <subsection name="LBFGS-VECTORS" rep="TEXTFIELD">[integer] Sets the number of correction vectors used by the limitedmemory
 L-BFGS optimization routine. The current maximum allowable value, and the
 default in the absence of the LBFGS-VECTORS keyword is 15.
		</subsection>
      <subsection name="MAXITER" rep="TEXTFIELD">[integer] Sets the maximum number of minimization iterations that will be
 allowed for any Tinker program that uses any of the nonlinear optimization routines. The
 default value in the absence of this keyword is program dependent, but is always set to a
 very large number.
		</subsection>
      <subsection name="NEWHESS" rep="TEXTFIELD">[integer] Sets the number of algorithmic iterations between recomputation of
 the Hessian matrix. At present this keyword applies exclusively to optimizations using the
 Truncated Newton method. The default value in the absence of this keyword is 1, i.e., the
 Hessian is computed on every iteration.
		</subsection>
      <subsection name="NEXTITER" rep="TEXTFIELD">[integer] Sets the iteration number to be used for the first iteration of the
 current computation. At present this keyword applies to optimization procedures where its
 use can effect convergence criteria, timing of restarts, and so forth. The default in the
 absence of this keyword is to take the initial iteration as iteration 1.
		</subsection>
      <subsection name="SLOPEMAX" rep="TEXTFIELD">[real] This keyword and its modifying value set the maximum allowed size
 of the ratio between the current and initial projected gradients during the line search phase
 of conjugate gradient or truncated Newton optimizations. If this ratio exceeds SLOPEMAX,
 then the initial step size is reduced by a factor of 10. The default value is usually set to
 10000.0 when not specified via the SLOPEMAX keyword.
		</subsection>
      <subsection name="STEPMAX" rep="TEXTFIELD">[real] This keyword and its modifying value set the maximum size of an
 individual step during the line search phase of conjugate gradient or truncated Newon
 optimizations. The step size is computed as the norm of the vector of changes in parameters
 being optimized. The default value depends on the particular Tinker program, but is
 usually in the range from 1.0 to 5.0 when not specified via the STEPMAX keyword.
		</subsection>
      <subsection name="STEPMIN" rep="TEXTFIELD">[real] This keyword and its modifying value set the minimum size of an
 individual step during the line search phase of conjugate gradient or truncated Newon
 optimizations. The step size is computed as the norm of the vector of changes in parameters
 being optimized. The default value is usually set to about 10-16 when not specified via the
 STEPMIN keyword.
		</subsection>
      <subsection name="STEEPEST-DESCENT" rep="CHECKBOX">This keyword forces the L-BFGS optimization routine used by
 the MINIMIZE program and other programs to perform steepest descent minimization. This
 option can be useful in conjunction with small step sizes for following minimum energy
 paths, but is generally inferior to the L-BFGS default for most optimization purposes.
		</subsection>
    </section>
    <section name="Dynamics">
      <subsection name="ANISO-PRESSURE" rep="CHECKBOX">ANISO-PRESSURE DOCUMENTATION...
		</subsection>
      <subsection name="BAROSTAT" rep="COMBOBOX">[BERENDSON/BUSSI/NOSE-HOOVER/MONTECARLO]
 This keyword selects a barostat algorithm for used to control pressure during molecular dynamics.
 Four modifiers are available cooresponding to the original Berendsen coupling, Bussi-Parrinello
 method, Nose-Hoover extended dynamics method, and a Monte Carlo procedure. The default
 in the absence of the BAROSTAT keyword is to use the BERENDSEN algorithm.
        <Value name="BERENDSON"/>
        <Value name="BUSSI"/>
        <Value name="NOSE-HOOVER"/>
        <Value name="MONTECARLO"/>
        <Value name="DEFAULT"/>
      		</subsection>
      <subsection name="BEEMAN-MIXING" rep="TEXTFIELD">[integer] BEEMAN-MIXING DOCUMENTATION...
		</subsection>
      <subsection name="GAMMA" rep="TEXTFIELD">[real] Sets the value of the gamma angle of a crystal unit cell, i.e., the angle between
 the a-axis and b-axis of a unit cell, or, equivalently, the angle between the X-axis and Z-axis
 of a periodic box. The default value in the absence of the GAMMA keyword is to set the ?
 angle equal to the a angle as given by the keyword ALPHA.
		</subsection>
      <subsection name="COLLISION" rep="TEXTFIELD">[real] Sets the value of the random collision frequency used in the Andersen
 stochastic collision dynamics thermostat. The supplied value has units of fs-1 atom-1 and is
 multiplied internal to Tinker by the time step in fs and N-2/3 where N is the number of
 atoms. The default value used in the absence of the COLLISION keyword is 0.1 which is
 appropriate for many systems but may need adjustment to achieve adequate COMBOBOXerature
 control without perturbing the dynamics.
		</subsection>
      <subsection name="COMPRESS" rep="TEXTFIELD">[real] Sets the value of the bulk solvent isothermal compressibility in Atm-1
 for use during pressure computation and scaling in molecular dynamics computations. The
 default value used in the absence of the COMPRESS keyword is 0.000046, appropriate for
 water. This parameter serves as a scale factor for the Groningen-style pressure bath coupling time,
 and its exact value should not be of critical importance.
		</subsection>
      <subsection name="DEGREES-FREEDOM" rep="TEXTFIELD">[integer] This keyword allows manual setting of the number of
 degrees of freedom during a dynamics calculation. The integer modifier is used by
 thermostating methods and in other places as the number of degrees of freedom, overriding
 the value determined by the Tinker code at dynamics startup. In the absence of the
 keyword, the programs will automatically compute the correct value based on the number of
 atoms active during dynamics, bond or other constrains, and use of periodic boundary
 conditions.
		</subsection>
      <subsection name="FRICTION" rep="TEXTFIELD">[real] Sets the value of the frictional coefficient in ps-1 for use with stochastic
 dynamics. The default value used in the absence of the FRICTION keyword is 91.0, which is
 generally appropriate for water.
		</subsection>
      <subsection name="FRICTION-SCALING" rep="CHECKBOX">No description yet.
		</subsection>
      <subsection name="INTEGRATOR" rep="COMBOBOX">[VERLET/BEEMAN/RESPA/BAOAB/NOSE-HOOVER/BUSSI/GHMC/STOCHASTIC/RIGIDBODY]
 Chooses the integration method for propagation of dynamics trajectories. The keyword is followed on
 the same line by the name of the option. Standard Newtonian MD can be run using either
 VERLET for the Velocity Verlet method, or BEEMAN for the velocity form of Bernie Brooks' Better Beeman
 method. RESPA uses a simple multiple time step method that separated valence and nonbonded terms.
 A Velocity Verlet-based stochastic dynamics trajectory is selected by the STOCHASTIC modifier.
 A rigid-body dynamics method is selected by the RIGIDBODY modifier. The default integration scheme
 is MD using the BEEMAN method.
		   <Value name="VERLET"/>
        <Value name="BEEMAN"/>
        <Value name="RESPA"/>
        <Value name="BAOAB"/>
        <Value name="NOSE-HOOVER"/>
        <Value name="BUSSI"/>
        <Value name="GHMC"/>
        <Value name="STOCHASTIC"/>
        <Value name="RIGIDBODY"/>
        <Value name="DEFAULT"/>
      </subsection>
      <subsection name="NOSE-MASS" rep="TEXTFIELD"> [2 reals]
 Sets the hypothetical mass in Daltons of each of the two chain particles for the Nose-Hoover thermostat.
 If only a single real number modifier is given, its value is used for both chains. The default in the
 absence of this keyword is to use a mass of 10 Daltons for each Nose-Hoover chain.
		</subsection>
      <subsection name="TAU-PRESSURE" rep="TEXTFIELD">[real]
 Sets the coupling time in picoseconds for the Berendsen pressure bath coupling used to control
 the system pressure during molecular dynamics calculations. A default value of 2.0 is used for
 TAU-PRESSURE in the absence of the keyword.
		</subsection>
      <subsection name="TAU-TEMPERATURE" rep="TEXTFIELD">[real]
 Sets the coupling time in picoseconds for Berendsen temperature bath coupling used to control
 the system temperature during molecular dynamics calculations. A default value of 0.1 is used
 for TAU-TEMPERATURE in the absence of the keyword.
		</subsection>
      <subsection name="THERMOSTAT" rep="COMBOBOX">[BUSSI/BERENDSEN/ANDERSEN/NOSE-HOOVER]
 This keyword selects a thermostat algorithm for used to control temperature during molecular dynamics.
 Four modifiers are available cooresponding to the Bussi-Parinello stochastic coupling, original Berendsen
 bath coupling, Andersen stochastic collision, and Nose-Hoover extended dynamics methods. The default
 in the absence of the THERMOSTAT keyword is to use the BUSSI algorithm.
        <Value name="BUSSI"/>
        <Value name="BERENDSEN"/>
        <Value name="ANDERSEN"/>
        <Value name="NOSE-HOOVER"/>
        <Value name="DEFAULT"/>
      </subsection>
    </section>
    <section name="Transition State">
      <subsection name="DIVERGE" rep="TEXTFIELD">[real] This keyword is used by the SADDLE program to set the maximum
 allowed value of the ratio of the gradient length along the path to the total gradient norm at
 the end of a cycle of minimization perpendicular to the path. If the value provided by the
 DIVERGE keyword is exceeded, then another cycle of maximization along the path is
 required. A default value of 0.005 is used in the absence of the DIVERGE keyword.
		</subsection>
      <subsection name="GAMMAMIN" rep="TEXTFIELD">[real] Sets the convergence target value for ? during searches for maxima
 along the quadratic synchronous transit used by the SADDLE program. The value of ? is the
 square of the ratio of the gradient projection along the path to the total gradient. A default
 value of 0.00001 is used in the absence of the GAMMAMIN keyword.
		</subsection>
      <subsection name="REDUCE" rep="TEXTFIELD">[real] Specifies the fraction between zero and one by which the path between
 starting and final conformational state will be shortened at each major cycle of the transition
 state location algorithm implemented by the SADDLE program. This causes the path
 endpoints to move up and out of the terminal structures toward the transition state region.
 In favorable cases, a nonzero value of the REDUCE modifier can speed convergence to the
 transition state. The default value in the absence of the REDUCE keyword is zero.
		</subsection>
      <subsection name="SADDLEPOINT" rep="CHECKBOX">The presence of this keyword allows Newton-style second derivativebased
 optimization routine used by NEWTON, NEWTROT and other programs to converge
 to saddlepoints as well as minima on the potential surface. By default, in the absence of the
 SADDLEPOINT keyword, checks are applied that prevent convergence to stationary points
 having directions of negative curvature.
		</subsection>
    </section>
    <section name="Distance Geometry">
      <subsection name="TRIAL-DISTANCE" rep="TEXTFIELD">[CLASSIC/RANDOM/TRICOR/HAVEL integer/PAIRWISE integer]
 Sets the method for selection of a trial distance matrix during distance geometry
 computations. The keyword takes a modifier that selects the method to be used. The HAVEL
 and PAIRWISE modifiers also require an additional integer value that specifies the number
 of atoms used in metrization and the percentage of metrization, respectively. The default in
 the absence of this keyword is to use the PAIRWISE method with 100 percent metrization.
 Further information on the various methods is given with the description of the Tinker
 distance geometry program.
		</subsection>
      <subsection name="TRIAL-DISTRIBUTION" rep="TEXTFIELD">[real] Sets the initial value for the mean of the Gaussian
 distribution used to select trial distances between the lower and upper bounds during
 distance geometry computations. The value given must be between 0 and 1 which represent
 the lower and upper bounds respectively. This keyword is rarely needed since Tinker will
 usually be able to choose a reasonable value by default.
		</subsection>
    </section>
    <section name="Random Number">
      <subsection name="RANDOMSEED" rep="TEXTFIELD">[integer] Followed by an integer value, this keyword sets the initial
 seed value for the random number generator used by Tinker. Setting RANDOMSEED to
 the same value as an earlier run will allow exact reproduction of the earlier calculation.
 (Note that this will not hold across different machine types.) RANDOMSEED should be set
 to a positive integer less than about 2 billion. In the absence of the RANDOMSEED keyword
 the seed is chosen randomly based upon the number of seconds that have elapsed in the
 current decade.
		</subsection>
    </section>
    <section name="Free Energy Perturbation">
      <subsection name="LAMBDA" rep="TEXTFIELD">[real] This keyword sets the value of the lambda path parameter for free energy
 perturbation calculations. The real number modifier specifies the position along the mutation
 path and must be a number in the range from 0 (initial state) to 1 (final state). The actual
 atoms involved in the mutation are given separately in individual MUTATE keyword lines.
		</subsection>
      <subsection name="MUTATE" rep="TEXTFIELD">[3 integers] This keyword is used to specify atoms to be mutated during free
 energy perturbation calculations. The first integer modifier gives the atom number of an
 atom in the current system. The final two modifier values give the atom types corresponding
 the the lambda=0 and lambda=1 states of the specified atom.
		</subsection>
    </section>
    <section name="Partial Structure">
      <subsection name="ACTIVE" rep="EDITCOMBOBOX">[integer list] Sets the list of active atoms during a Tinker computation.
 Individual potential energy terms are computed when at least one atom involved in the term
 is active. For Cartesian space calculations, active atoms are those allowed to move. For
 torsional space calculations, rotations are allowed when all atoms on one side of the rotated
 bond are active. Multiple ACTIVE lines can be present in the keyfile and are treated
 cumulatively. On each line the keyword can be followed by one or more atom numbers or
 atom ranges. The presence of any ACTIVE keyword overrides any INACTIVE keywords in
 the keyfile.
		</subsection>
      <subsection name="INACTIVE" rep="EDITCOMBOBOX">[integer list] Sets the list of inactive atoms during a Tinker computation.
 Individual potential energy terms are not computed when all atoms involved in the term are
 inactive. For Cartesian space calculations, inactive atoms are not allowed to move. For
 torsional space calculations, rotations are not allowed when there are inactive atoms on both
 sides of the rotated bond. Multiple INACTIVE lines can be present in the keyfile, and on
 each line the keyword can be followed by one or more atom numbers or ranges. If any
 INACTIVE keys are found, all atoms are set to active except those listed on the INACTIVE
 lines. The ACTIVE keyword overrides all INACTIVE keywords found in the keyfile.
		</subsection>
      <subsection name="ACTIVE-SPHERE" rep="EDITCOMBOBOX">[4 reals, or 1 integer and 1 real] This keyword provides an alternative to the
 ACTIVE and INACTIVE keywords for specification of subsets of active atoms. If four real
 number modifiers are provided, the first three are taken as X-, Y- and Z-coordinates and the
 fourth is the radius of a sphere centered at these coordinates. In this case, all atoms within
 the sphere at the start of the calculation are active throughout the calculation, while all other
 atoms are inactive. Similarly if one integer and real number are given, an active sphere
 with radius set by the real is centered on the system atom with atom number given by the
 integer modifier. Multiple ACTIVE-SPHERE keyword lines can be present in a single keyfile, and the
 list of active atoms specified by the spheres is cumulative.
		</subsection>
      <subsection name="GROUP" rep="EDITCOMBOBOX">[integer, integer list] This keyword defines an atom group as a substructure
 within the full input molecular structure. The value of the first integer is the group number
 which must be in the range from 1 to the maximum number of allowed groups. The
 remaining intergers give the atom or atoms contained in this group as one or more atom
 numbers or ranges. Multiple keyword lines can be used to specify additional atoms in the
 same group. Note that an atom can only be in one group, the last group to which it is
 assigned is the one used.
		</subsection>
      <subsection name="GROUP-SELECT" rep="EDITCOMBOBOX">[2 integers, real] This keyword gives the weight in the final potential
 energy of a specified set of intra- or intergroup interactions. The integer modifiers give the
 group numbers of the groups involved. If the two numbers are the same, then an intragroup
 set of interactions is specified. The real modifier gives the weight by which all energetic
 interactions in this set will be multiplied before incorporation into the final potential energy.
 If omitted as a keyword modifier, the weight will be set to 1.0 by default. If any SELECTGROUP
 keywords are present, then any set of interactions not specified in a SELECTGROUP
 keyword is given a zero weight. The default when no SELECT-GROUP keywords
 are specified is to use all intergroup interactions with a weight of 1.0 and to set all
 intragroup interactions to zero.
		</subsection>
      <subsection name="GROUP-INTER" rep="CHECKBOX">This keyword assigns a value of 1.0 to all inter-group interactions and a
 value of 0.0 to all intra-group interactions. For example, combination with the GROUPMOLECULE
 keyword provides for rigid-body calculations.
		</subsection>
      <subsection name="GROUP-INTRA" rep="CHECKBOX">This keyword assigns a value of 1.0 to all intra-group interactions and a
 value of 0.0 to all inter-group interactions.
		</subsection>
      <subsection name="GROUP-MOLECULE" rep="CHECKBOX">This keyword sets each individual molecule in the system to be a
 separate atom group, but does not assign weights to group-group interactions.
		</subsection>
    </section>
    <section name="Constriant And Restraint">
      <subsection name="BASIN" rep="TEXTFIELD">[2 reals] Presence of this keyword turns on a basin restraint potential function
 that serves to drive the system toward a compact structure. The actual function is a
 Gaussian of the form Ebasin = S A exp[-B R2], summed over all pairs of atoms where R is the
 distance between atoms. The A and B values are the depth and width parameters given as
 modifiers to the BASIN keyword. This potential is currently used to control the degree of
 expansion during potential energy smooth procedures through the use of shallow, broad
 basins.
		</subsection>
      <subsection name="WALL" rep="TEXTFIELD">[real] Sets the radius of a spherical boundary used to maintain droplet boundary
 conditions. The real modifier specifies the desired approximate radius of the droplet. In
 practice, an artificial van der Waals wall is constructed at a fixed buffer distance of 2.5 ??
 outside the specified radius. The effect is that atoms which atCOMBOBOXt to move outside the
 region defined by the droplet radius will be forced toward the center.
		</subsection>
      <subsection name="ENFORCE-CHIRALITY" rep="CHECKBOX">This keyword causes the chirality found at chiral tetravalent
 centers in the input structure to be maintained during Tinker calculations. The test for
 chirality is not exhaustive; two identical monovalent atoms connected to a center cause
 it to be marked as non-chiral, but large equivalent substituents are not detected. Trivalent
 ??????chiral?????? centers, for example the alpha carbon in united-atom protein structures, are not
 enforced as chiral.
		</subsection>
      <subsection name="RATTLE" rep="CHECKBOXES">[BONDS/ANGLES/DIATOMIC/TRIATOMIC/WATER] Invokes the rattle
 algorithm, a velocity version of shake, on portions of a molecular system during a molecular
 dynamic calculation. The RATTLE keyword can be followed by any of the modifiers shown, in
 which case all occurrences of the modifier species are constrained at ideal values taken from
 the bond and angle parameters of the force field in use. In the absence of any modifier,
 RATTLE constrains all bonds to hydrogen atoms at ideal bond lengths.
         <Value name="BONDS"/>
        <Value name="ANGLES"/>
        <Value name="DIATOMIC"/>
        <Value name="TRIATOMIC"/>
        <Value name="WATER"/>
      </subsection>
      <subsection name="RATTLE-DISTANCE" rep="EDITCOMBOBOX">[2 integers] This keyword allows the use of rattle (see above) on a the
 bond between the two atoms whose numbers are specified on the keyword line. If the two
 atoms are involved in a covalent bond, then their distance is constrained to the ideal bond
 length from the force field. For nonbonded atoms, the rattle constraint fixes their distance at
 the distance in the input coordinate file.
		</subsection>
      <subsection name="RESTRAIN-ANGLE" rep="EDITCOMBOBOX">[3 integers and 3 reals] This keyword implements a flat-welled harmonic potential
 that can be used to restrain the angle between three atoms to lie within a specified angle range. The initial
 integer modifiers contains the atom numbers of the three atoms whose angle is to be restrained. The first
 real modifier is the force constant in kcal/degree2 for the restraint. The last two real number modifiers give
 the lower and upper bounds in degrees on the allowed angle values. If the angle lies between the lower and
 upper bounds, the restraint potential is zero. Outside the bounds, the harmonic restraint is applied. If the
 angle range modifiers are omitted, then the atoms are restrained to the angle found in the input structure. If
 the force constant is also omitted, a default value of 10.0 is used.
		</subsection>
      <subsection name="RESTRAIN-DISTANCE" rep="EDITCOMBOBOX">[2 integers and 3 reals] This keyword implements a flat-welled harmonic
 potential that can be used to restrain two atoms to lie within a specified distance range. The initial integer
 modifiers contains the atom numbers of the two atoms to be restrained. The first two real number modifiers
 give the lower and upper bounds in ??ngstroms on the allowed distance values. If the interatomic distance
 lies between the lower and upper bounds, the restraint potential is zero. Outside the bounds, the harmonic
 restraint is applied. If the distance range modifiers are omitted, then the atoms are restrained to the
 interatomic distance found in the input structure. If the force constant is also omitted, a default value of
 100.0 is used.
		</subsection>
      <subsection name="RESTRAIN-GROUPS" rep="EDITCOMBOBOX">[2 integers and 3 reals] This keyword implements a flat-welled harmonic
 distance restraint between the centers-of-mass of two groups of atoms. The integer modifiers are the
 numbers of the two groups which must be defined separately via the GROUP keyword. The first real
 modifier is the force constant in kcal/??2 for the restraint. The last two real number modifiers give the lower
 and upper bounds in ??ngstroms on the allowed distance values. If the distance range modifiers are omitted,
 then the atoms are restrained to the intergroup distance found in the input structure. If the force constant is
 also omitted, a default value of 100.0 is used.
		</subsection>
      <subsection name="RESTRAIN-POSITION" rep="EDITCOMBOBOX">[1 integer and 5 reals] This keyword provides the ability to restrain an
 individual atom to a specified coordinate position. The initial integer modifier contains the atom number of
 the atom to be restrained. The first real modifier sets the force constant in kcal/??2 for the harmonic restraint
 potential. The next three real number modifiers give the X-, Y- and Z-coordinates to which the atom is
 tethered. The final real modifier defines a sphere around the specified coordinates within which the
 restraint value is zero. If all the real modifiers are omitted, then the atom is restrained to the origin. If the
 force constant is also omitted, a default value of 100.0 is used.
		</subsection>
      <subsection name="RESTRAIN-TORSION" rep="EDITCOMBOBOX">[4 integers and 3 reals] This keyword implements a flat-welled harmonic
 potential that can be used to restrain the torsional angle between four atoms to lie within a specified angle
 range. The initial integer modifiers contains the atom numbers of the four atoms whose torsional angle,
 computed in the atom order listed, is to be restrained. The first real modifier gives a force constant in
 kcal/degree2. The last two real number modifiers give the lower and upper bounds in degrees on the allowed
 torsional angle values. The angle values given can wrap around across -180 and +180 degrees. Outside the
 allowed angle range, the harmonic restraint is applied. If the angle range modifiers are omitted, then the
 atoms are restrained to the torsional angle found in the input structure. If the force constant is also omitted,
 a default value of 1.0 is used.
		</subsection>
    </section>
    <section name="Potential Smoothing">
      <subsection name="DEFORM" rep="TEXTFIELD">[real] Sets the amount of diffusion equation-style smoothing that will be
 applied to the potential energy surface when using the SMOOTH force field. The real
 number option is equivalent to the time value in the original Piela, et al. formalism; the
 larger the value, the greater the smoothing. The default value is zero, meaning that no
 smoothing will be applied.
		</subsection>
      <subsection name="DIFFUSE-CHARGE" rep="TEXTFIELD">[real] This keyword is used during potential function smoothing
 procedures to specify the effective diffusion coefficient to be applied to the smoothed form of
 the Coulomb???s Law charge-charge potential function. In the absence of the DIFFUSECHARGE
 keyword, a default value of 3.5 is used.
		</subsection>
      <subsection name="DIFFUSE-TORSION" rep="TEXTFIELD">[real] This keyword is used during potential function smoothing
 procedures to specify the effective diffusion coefficient to be applied to the smoothed form of
 the torsion angle potential function. In the absence of the DIFFUSE-TORSION keyword, a
 default value of 0.0225 is used.
		</subsection>
      <subsection name="DIFFUSE-VDW" rep="TEXTFIELD">[real] This keyword is used during potential function smoothing
 procedures to specify the effective diffusion coefficient to be applied to the smoothed
 Gaussian approximation to the Lennard-Jones van der Waals potential function. In the
 absence of the DIFFUSE-VDW keyword, a default value of 1.0 is used.
		</subsection>
      <subsection name="SMOOTHING" rep="COMBOBOX">[DEM/GDA/TOPHAT/STOPHAT] This keyword activates the potential
 energy smoothing methods. Several variations are available depending on the value of the
 modifier used: DEM= Diffusion Equation Method with a standard Gaussian kernel; GDA=
 Gaussian Density Annealing as proposed by the Straub group; TOPHAT= a local DEM-like
 method using a finite range tophat kernel; STOPHAT= shifted tophat smoothing.
		   <Value name="DEN"/>
        <Value name="GDA"/>
        <Value name="TOPHAT"/>
        <Value name="STOPHAT"/>
        <Value name="DEFAULT"/>
      </subsection>
    </section>
  </body>
</document>
