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
|
||
|
|
|
||
|
|
:link(lws,http://lammps.sandia.gov)
|
||
|
|
:link(ld,Manual.html)
|
||
|
|
:link(lc,Section_commands.html#comm)
|
||
|
|
|
||
|
|
:line
|
||
|
|
|
||
|
|
pair_style born/coul/long/cs command :h3
|
||
|
|
pair_style buck/coul/long/cs command :h3
|
||
|
|
|
||
|
|
[Syntax:]
|
||
|
|
|
||
|
|
pair_style style args :pre
|
||
|
|
|
||
|
|
style = {born/coul/long/cs} or {buck/coul/long/cs}
|
||
|
|
args = list of arguments for a particular style :ul
|
||
|
|
{born/coul/long/cs} args = cutoff (cutoff2)
|
||
|
|
cutoff = global cutoff for non-Coulombic (and Coulombic if only 1 arg) (distance units)
|
||
|
|
cutoff2 = global cutoff for Coulombic (optional) (distance units)
|
||
|
|
{buck/coul/long/cs} args = cutoff (cutoff2)
|
||
|
|
cutoff = global cutoff for Buckingham (and Coulombic if only 1 arg) (distance units)
|
||
|
|
cutoff2 = global cutoff for Coulombic (optional) (distance units) :pre
|
||
|
|
|
||
|
|
[Examples:]
|
||
|
|
|
||
|
|
pair_style born/coul/long/cs 10.0 8.0
|
||
|
|
pair_coeff 1 1 6.08 0.317 2.340 24.18 11.51 :pre
|
||
|
|
|
||
|
|
pair_style buck/coul/long/cs 10.0
|
||
|
|
pair_style buck/coul/long/cs 10.0 8.0
|
||
|
|
pair_coeff * * 100.0 1.5 200.0
|
||
|
|
pair_coeff 1 1 100.0 1.5 200.0 9.0 :pre
|
||
|
|
|
||
|
|
[Description:]
|
||
|
|
|
||
|
|
These pair styles are designed to be used with the adiabatic
|
||
|
|
core/shell model of "(Mitchell and Finchham)"_#MitchellFinchham. See
|
||
|
|
"Section_howto 25"_Section_howto.html#howto_25 of the manual for an
|
||
|
|
overview of the model as implemented in LAMMPS.
|
||
|
|
|
||
|
|
These pair styles are identical to the "pair_style
|
||
|
|
born/coul/long"_pair_born.html and "pair_style
|
||
|
|
buck/coul/long"_pair_buck.html styles, except they correctly treat the
|
||
|
|
special case where the distance between two charged core and shell
|
||
|
|
atoms in the same core/shell pair approach r = 0.0. This needs
|
||
|
|
special treatment when a long-range solver for Coulombic interactions
|
||
|
|
is also used, i.e. via the "kspace_style"_kspace_style.html command.
|
||
|
|
|
||
|
|
More specifically, the short-range Coulomb interaction between a core
|
||
|
|
and its shell should be turned off using the
|
||
|
|
"special_bonds"_special_bonds.html command by setting the 1-2 weight
|
||
|
|
to 0.0, which works because the core and shell atoms are bonded to
|
||
|
|
each other. This induces a long-range correction approximation which
|
||
|
|
fails at small distances (~< 10e-8). Therefore, the Coulomb term which
|
||
|
|
is used to calculate the correction factor is extended by a minimal
|
||
|
|
distance (r_min = 1.0-6) when the interaction between a core/shell
|
||
|
|
pair is treated, as follows
|
||
|
|
|
||
|
|
:c,image(Eqs/pair_cs.jpg)
|
||
|
|
|
||
|
|
where C is an energy-conversion constant, Qi and Qj are the charges on
|
||
|
|
the core and shell, epsilon is the dielectric constant and r_min is the
|
||
|
|
minimal distance.
|
||
|
|
|
||
|
|
[Restrictions:]
|
||
|
|
|
||
|
|
These pair styles are part of the CORESHELL package. They are only
|
||
|
|
enabled if LAMMPS was built with that package. See the "Making
|
||
|
|
LAMMPS"_Section_start.html#start_3 section for more info.
|
||
|
|
|
||
|
|
[Related commands:]
|
||
|
|
|
||
|
|
"pair_coeff"_pair_coeff.html, "pair_style born"_pair_born.html,
|
||
|
|
"pair_style buck"_pair_buck.html
|
||
|
|
|
||
|
|
[Default:] none
|
||
|
|
|
||
|
|
:line
|
||
|
|
|
||
|
|
:link(MitchellFinchham)
|
||
|
|
[(Mitchell and Finchham)] Mitchell, Finchham, J Phys Condensed Matter,
|
||
|
|
5, 1031-1038 (1993).
|