forked from lijiext/lammps
145 lines
4.2 KiB
Plaintext
145 lines
4.2 KiB
Plaintext
"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
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:link(lws,http://lammps.sandia.gov)
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:link(ld,Manual.html)
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:link(lc,Section_commands.html#comm)
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:line
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pair_style list command :h3
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[Syntax:]
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pair_style list listfile cutoff keyword :pre
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listfile = name of file with list of pairwise interactions
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cutoff = global cutoff (distance units)
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keyword = optional flag {nocheck} or {check} (default is {check}) :ul
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[Examples:]
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pair_style list restraints.txt 200.0
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pair_coeff * * :pre
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pair_style hybrid/overlay lj/cut 1.1225 list pair_list.txt 300.0
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pair_coeff * * lj/cut 1.0 1.0
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pair_coeff 3* 3* list :pre
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[Description:]
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Style {list} computes interactions between explicitly listed pairs of
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atoms with the option to select functional form and parameters for
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each individual pair. Because the parameters are set in the list
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file, the pair_coeff command has no parameters (but still needs to be
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provided). The {check} and {nocheck} keywords enable/disable a test
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that checks whether all listed bonds were present and computed.
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This pair style can be thought of as a hybrid between bonded,
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non-bonded, and restraint interactions. It will typically be used as
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an additional interaction within the {hybrid/overlay} pair style. It
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currently supports three interaction styles: a 12-6 Lennard-Jones, a
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Morse and a harmonic potential.
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The format of the list file is as follows:
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one line per pair of atoms :ulb,l
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empty lines will be ignored :l
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comment text starts with a '#' character :l
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line syntax: {ID1 ID2 style coeffs cutoff} :l
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ID1 = atom ID of first atom
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ID2 = atom ID of second atom
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style = style of interaction
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coeffs = list of coeffs
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cutoff = cutoff for interaction (optional) :pre
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:ule
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The cutoff parameter is optional. If not specified, the global cutoff
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is used.
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Here is an example file:
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# this is a comment :pre
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15 259 lj126 1.0 1.0 50.0
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15 603 morse 10.0 1.2 2.0 10.0 # and another comment
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18 470 harmonic 50.0 1.2 5.0 :pre
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The style {lj126} computes pairwise interactions with the formula
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:c,image(Eqs/pair_lj.jpg)
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and the coefficients:
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epsilon (energy units)
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sigma (distance units) :ul
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The style {morse} computes pairwise interactions with the formula
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:c,image(Eqs/pair_morse.jpg)
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and the coefficients:
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D0 (energy units)
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alpha (1/distance units)
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r0 (distance units) :ul
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The style {harmonic} computes pairwise interactions with the formula
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:c,image(Eqs/bond_harmonic.jpg)
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and the coefficients:
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K (energy units)
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r0 (distance units) :ul
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Note that the usual 1/2 factor is included in K.
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:line
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[Mixing, shift, table, tail correction, restart, rRESPA info]:
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This pair style does not support mixing since all parameters are
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explicit for each pair.
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The "pair_modify"_pair_modify.html shift option is supported by this
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pair style.
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The "pair_modify"_pair_modify.html table and tail options are not
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relevant for this pair style.
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This pair style does not write its information to "binary restart
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files"_restart.html, so pair_style and pair_coeff commands need
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to be specified in an input script that reads a restart file.
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This pair style can only be used via the {pair} keyword of the
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"run_style respa"_run_style.html command. It does not support the
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{inner}, {middle}, {outer} keywords.
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:line
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[Restrictions:]
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This pair style does not use a neighbor list and instead identifies
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atoms by their IDs. This has two consequences: 1) The cutoff has to be
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chosen sufficiently large, so that the second atom of a pair has to be
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a ghost atom on the same node on which the first atom is local;
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otherwise the interaction will be skipped. You can use the {check}
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option to detect, if interactions are missing. 2) Unlike other pair
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styles in LAMMPS, an atom I will not interact with multiple images of
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atom J (assuming the images are within the cutoff distance), but only
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with the nearest image.
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This style is part of the USER-MISC package. It is only enabled if
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LAMMPS is build with that package. See the "Making of
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LAMMPS"_Section_start.html#3 section for more info.
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[Related commands:]
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"pair_coeff"_pair_coeff.html,
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"pair_style hybrid/overlay"_pair_hybrid.html,
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"pair_style lj/cut"_pair_lj.html,
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"pair_style morse"_pair_morse.html,
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"bond_style harmonic"_bond_harmonic.html
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[Default:] none
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