forked from lijiext/lammps
84 lines
2.9 KiB
Plaintext
84 lines
2.9 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 born/coul/long/cs command :h3
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pair_style buck/coul/long/cs command :h3
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[Syntax:]
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pair_style style args :pre
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style = {born/coul/long/cs} or {buck/coul/long/cs}
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args = list of arguments for a particular style :ul
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{born/coul/long/cs} args = cutoff (cutoff2)
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cutoff = global cutoff for non-Coulombic (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/cs} 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 born/coul/long/cs 10.0 8.0
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pair_coeff 1 1 6.08 0.317 2.340 24.18 11.51 :pre
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pair_style buck/coul/long/cs 10.0
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pair_style buck/coul/long/cs 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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These pair styles are designed to be used with the adiabatic
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core/shell model of "(Mitchell and Finchham)"_#MitchellFinchham. See
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"Section_howto 25"_Section_howto.html#howto_25 of the manual for an
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overview of the model as implemented in LAMMPS.
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These pair styles are identical to the "pair_style
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born/coul/long"_pair_born.html and "pair_style
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buck/coul/long"_pair_buck.html styles, except they correctly treat the
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special case where the distance between two charged core and shell
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atoms in the same core/shell pair approach r = 0.0. This needs
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special treatment when a long-range solver for Coulombic interactions
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is also used, i.e. via the "kspace_style"_kspace_style.html command.
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More specifically, the short-range Coulomb interaction between a core
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and its shell should be turned off using the
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"special_bonds"_special_bonds.html command by setting the 1-2 weight
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to 0.0, which works because the core and shell atoms are bonded to
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each other. This induces a long-range correction approximation which
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fails at small distances (~< 10e-8). Therefore, the Coulomb term which
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is used to calculate the correction factor is extended by a minimal
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distance (r_min = 1.0-6) when the interaction between a core/shell
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pair is treated, as follows
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:c,image(Eqs/pair_cs.jpg)
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where C is an energy-conversion constant, Qi and Qj are the charges on
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the core and shell, epsilon is the dielectric constant and r_min is the
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minimal distance.
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[Restrictions:]
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These pair styles are part of the CORESHELL package. They are only
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enabled if LAMMPS was built with that package. See the "Making
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LAMMPS"_Section_start.html#start_3 section 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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"pair_style buck"_pair_buck.html
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[Default:] none
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:line
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:link(MitchellFinchham)
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[(Mitchell and Finchham)] Mitchell, Finchham, J Phys Condensed Matter,
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5, 1031-1038 (1993).
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