forked from lijiext/lammps
192 lines
7.3 KiB
Plaintext
192 lines
7.3 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,Commands_all.html)
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:line
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pair_style buck command :h3
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pair_style buck/gpu command :h3
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pair_style buck/intel command :h3
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pair_style buck/kk command :h3
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pair_style buck/omp command :h3
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pair_style buck/coul/cut command :h3
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pair_style buck/coul/cut/gpu command :h3
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pair_style buck/coul/cut/intel command :h3
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pair_style buck/coul/cut/kk command :h3
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pair_style buck/coul/cut/omp command :h3
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pair_style buck/coul/long command :h3
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pair_style buck/coul/long/gpu command :h3
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pair_style buck/coul/long/intel command :h3
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pair_style buck/coul/long/kk command :h3
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pair_style buck/coul/long/omp command :h3
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pair_style buck/coul/msm command :h3
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pair_style buck/coul/msm/omp command :h3
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[Syntax:]
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pair_style style args :pre
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style = {buck} or {buck/coul/cut} or {buck/coul/long} or {buck/coul/msm}
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args = list of arguments for a particular style :ul
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{buck} args = cutoff
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cutoff = global cutoff for Buckingham interactions (distance units)
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{buck/coul/cut} args = cutoff (cutoff2)
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cutoff = global cutoff for Buckingham (and Coulombic if only 1 arg) (distance units)
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cutoff2 = global cutoff for Coulombic (optional) (distance units)
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{buck/coul/long} args = cutoff (cutoff2)
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cutoff = global cutoff for Buckingham (and Coulombic if only 1 arg) (distance units)
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cutoff2 = global cutoff for Coulombic (optional) (distance units)
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{buck/coul/msm} args = cutoff (cutoff2)
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cutoff = global cutoff for Buckingham (and Coulombic if only 1 arg) (distance units)
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cutoff2 = global cutoff for Coulombic (optional) (distance units) :pre
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[Examples:]
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pair_style buck 2.5
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pair_coeff * * 100.0 1.5 200.0
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pair_coeff * * 100.0 1.5 200.0 3.0 :pre
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pair_style buck/coul/cut 10.0
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pair_style buck/coul/cut 10.0 8.0
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pair_coeff * * 100.0 1.5 200.0
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pair_coeff 1 1 100.0 1.5 200.0 9.0
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pair_coeff 1 1 100.0 1.5 200.0 9.0 8.0 :pre
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pair_style buck/coul/long 10.0
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pair_style buck/coul/long 10.0 8.0
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pair_coeff * * 100.0 1.5 200.0
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pair_coeff 1 1 100.0 1.5 200.0 9.0 :pre
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pair_style buck/coul/msm 10.0
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pair_style buck/coul/msm 10.0 8.0
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pair_coeff * * 100.0 1.5 200.0
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pair_coeff 1 1 100.0 1.5 200.0 9.0 :pre
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[Description:]
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The {buck} style computes a Buckingham potential (exp/6 instead of
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Lennard-Jones 12/6) given by
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:c,image(Eqs/pair_buck.jpg)
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where rho is an ionic-pair dependent length parameter, and Rc is the
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cutoff on both terms.
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The styles with {coul/cut} or {coul/long} or {coul/msm} add a
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Coulombic term as described for the "lj/cut"_pair_lj.html pair styles.
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For {buck/coul/long} and {buc/coul/msm}, an additional damping factor
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is applied to the Coulombic term so it can be used in conjunction with
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the "kspace_style"_kspace_style.html command and its {ewald} or {pppm}
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or {msm} option. The Coulombic cutoff specified for this style means
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that pairwise interactions within this distance are computed directly;
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interactions outside that distance are computed in reciprocal space.
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If one cutoff is specified for the {born/coul/cut} and
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{born/coul/long} and {born/coul/msm} styles, it is used for both the
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A,C and Coulombic terms. If two cutoffs are specified, the first is
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used as the cutoff for the A,C terms, and the second is the cutoff for
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the Coulombic term.
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Note that these potentials are related to the "Born-Mayer-Huggins
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potential"_pair_born.html.
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NOTE: For all these pair styles, the terms with A and C are always
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cutoff. The additional Coulombic term can be cutoff or long-range (no
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cutoff) depending on whether the style name includes coul/cut or
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coul/long or coul/msm. If you wish the C/r^6 term to be long-range
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(no cutoff), then see the "pair_style
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buck/long/coul/long"_pair_buck_long.html command.
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The following coefficients must be defined for each pair of atoms
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types via the "pair_coeff"_pair_coeff.html command as in the examples
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above, or in the data file or restart files read by the
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"read_data"_read_data.html or "read_restart"_read_restart.html
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commands:
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A (energy units)
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rho (distance units)
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C (energy-distance^6 units)
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cutoff (distance units)
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cutoff2 (distance units) :ul
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The second coefficient, rho, must be greater than zero.
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The coefficients A, rho, and C can be written as analytical expressions
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of epsilon and sigma, in analogy to the Lennard-Jones potential
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"(Khrapak)"_#Khrapak.
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The latter 2 coefficients are optional. If not specified, the global
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A,C and Coulombic cutoffs are used. If only one cutoff is specified,
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it is used as the cutoff for both A,C and Coulombic interactions for
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this type pair. If both coefficients are specified, they are used as
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the A,C and Coulombic cutoffs for this type pair. You cannot specify
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2 cutoffs for style {buck}, since it has no Coulombic terms.
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For {buck/coul/long} only the LJ cutoff can be specified since a
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Coulombic cutoff cannot be specified for an individual I,J type pair.
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All type pairs use the same global Coulombic cutoff specified in the
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pair_style command.
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:line
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Styles with a {gpu}, {intel}, {kk}, {omp}, or {opt} suffix are
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functionally the same as the corresponding style without the suffix.
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They have been optimized to run faster, depending on your available
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hardware, as discussed on the "Speed packages"_Speed_packages.html doc
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page. The accelerated styles take the same arguments and should
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produce the same results, except for round-off and precision issues.
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These accelerated styles are part of the GPU, USER-INTEL, KOKKOS,
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USER-OMP and OPT packages, respectively. They are only enabled if
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LAMMPS was built with those packages. See the "Build
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package"_Build_package.html doc page for more info.
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You can specify the accelerated styles explicitly in your input script
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by including their suffix, or you can use the "-suffix command-line
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switch"_Run_options.html when you invoke LAMMPS, or you can use the
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"suffix"_suffix.html command in your input script.
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See the "Speed packages"_Speed_packages.html doc page for more
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instructions on how to use the accelerated styles effectively.
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:line
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[Mixing, shift, table, tail correction, restart, rRESPA info]:
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These pair styles do not support mixing. Thus, coefficients for all
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I,J pairs must be specified explicitly.
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These styles support the "pair_modify"_pair_modify.html shift option
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for the energy of the exp() and 1/r^6 portion of the pair interaction.
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The {buck/coul/long} pair style supports the
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"pair_modify"_pair_modify.html table option to tabulate the
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short-range portion of the long-range Coulombic interaction.
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These styles support the pair_modify tail option for adding long-range
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tail corrections to energy and pressure for the A,C terms in the
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pair interaction.
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These styles write their information to "binary restart
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files"_restart.html, so pair_style and pair_coeff commands do not need
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to be specified in an input script that reads a restart file.
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These styles can only be used via the {pair} keyword of the "run_style
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respa"_run_style.html command. They do not support the {inner},
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{middle}, {outer} keywords.
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[Restrictions:]
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The {buck/coul/long} style is part of the KSPACE package. They are
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only enabled if LAMMPS was built with that package. See the "Build
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package"_Build_package.html doc page for more info.
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[Related commands:]
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"pair_coeff"_pair_coeff.html, "pair_style born"_pair_born.html
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[Default:] none
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:link(Khrapak)
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[(Khrapak)] Khrapak, Chaudhuri, and Morfill, J Chem Phys, 134, 054120 (2011).
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