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@ -10,25 +10,25 @@ dihedral_style charmm command :h3
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dihedral_style charmm/intel command :h3
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dihedral_style charmm/kk command :h3
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dihedral_style charmm/omp command :h3
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dihedral_style charmmfsh command :h3
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dihedral_style charmmfsw command :h3
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[Syntax:]
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dihedral_style style :pre
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style = {charmm} or {charmmfsh} :ul
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style = {charmm} or {charmmfsw} :ul
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[Examples:]
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dihedral_style charmm
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dihedral_style charmmfsh
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dihedral_style charmmfsw
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dihedral_coeff 1 0.2 1 180 1.0
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dihedral_coeff 2 1.8 1 0 1.0
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dihedral_coeff 1 3.1 2 180 0.5 :pre
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[Description:]
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The {charmm} and {charmmfsh} dihedral styles use the potential
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The {charmm} and {charmmfsw} dihedral styles use the potential
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:c,image(Eqs/dihedral_charmm.jpg)
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@ -38,10 +38,12 @@ field (see comment on weighting factors below). See
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"(Cornell)"_#dihedral-Cornell for a description of the AMBER force
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field.
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NOTE: The newer {charmmfsh} style was released in March 2017. We
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NOTE: The newer {charmmfsw} style was released in March 2017. We
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recommend it be used instead of the older {charmm} style when running
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a simulation with the CHARMM force field and Coulomb cutoffs, via the
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"pair_style lj/charmmfsw/coul/charmmfsh"_pair_charmm.html command.
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a simulation with the CHARMM force field, either with long-range
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Coulombics or a Coulomb cutoff, via the "pair_style
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lj/charmmfsw/coul/long"_pair_charmm.html and "pair_style
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lj/charmmfsw/coul/charmmfsh"_pair_charmm.html commands respectively.
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Otherwise the older {charmm} style is fine to use. See the discussion
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below and more details on the "pair_style charmm"_pair_charmm.html doc
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page.
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@ -86,17 +88,18 @@ default). Otherwise 1-4 non-bonded interactions in dihedrals will be
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computed twice.
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For simulations using the CHARMM force field with a Coulomb cutoff,
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the difference between the {charmm} and {charmmfsh} styles is in the
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the difference between the {charmm} and {charmmfsw} styles is in the
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computation of the 1-4 non-bond interactions, though only if the
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distance between the two atoms is within the switching region of the
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pairwise potential defined by the corresponding CHARMM pair style,
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i.e. within the outer cutoff specified for the pair style. The
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{charmmfsh} style should only be used when using the "pair_style
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lj/charmmfsw/coul/charmmfsh"_pair_charmm.html to make the Coulombic
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pairwise calculations consistent. Use the {charmm} style with
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long-range Coulombics or the older "pair_style
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lj/charmm/coul/charmm"_pair_charmm.html command. See the discussion
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on the "CHARMM pair_style"_pair_charmm.html doc page for details.
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{charmmfsw} style should only be used when using the corresponding
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"pair_style lj/charmmfsw/coul/charmmfsw"_pair_charmm.html or
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"pair_style lj/charmmfsw/coul/long"_pair_charmm.html commands. Use
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the {charmm} style with the older "pair_style"_pair_charmm.html
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commands that have just "charmm" in their style name. See the
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discussion on the "CHARMM pair_style"_pair_charmm.html doc page for
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details.
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Note that for AMBER force fields, which use pair styles with "lj/cut",
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the special_bonds 1-4 scaling factor should be set to the AMBER
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@ -104,7 +107,7 @@ defaults (1/2 and 5/6) and all the dihedral weighting factors (4th
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coeff above) must be set to 0.0. In this case, you can use any pair
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style you wish, since the dihedral does not need any Lennard-Jones
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parameter information and will not compute any 1-4 non-bonded
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interactions. Likewise the {charmm} or {charmmfsh} styles are
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interactions. Likewise the {charmm} or {charmmfsw} styles are
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identical in this case since no 1-4 non-bonded interactions are
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computed.
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Steve Plimpton