forked from lijiext/lammps
165 lines
6.0 KiB
Plaintext
165 lines
6.0 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 buck command :h3
|
|
pair_style buck/cuda command :h3
|
|
pair_style buck/omp command :h3
|
|
pair_style buck/coul/cut command :h3
|
|
pair_style buck/coul/cut/cuda command :h3
|
|
pair_style buck/coul/cut/omp command :h3
|
|
pair_style buck/coul/long command :h3
|
|
pair_style buck/coul/long/cuda command :h3
|
|
pair_style buck/coul/long/omp command :h3
|
|
|
|
[Syntax:]
|
|
|
|
pair_style style args :pre
|
|
|
|
style = {buck} or {buck/coul/cut} or {buck/coul/long}
|
|
args = list of arguments for a particular style :ul
|
|
{buck} args = cutoff
|
|
cutoff = global cutoff for Buckingham interactions (distance units)
|
|
{buck/coul/cut} args = cutoff (cutoff2)
|
|
cutoff = global cutoff for Buckingham (and Coulombic if only 1 arg) (distance units)
|
|
cutoff2 = global cutoff for Coulombic (optional) (distance units)
|
|
{buck/coul/long} 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 buck 2.5
|
|
pair_coeff * * 100.0 1.5 200.0
|
|
pair_coeff * * 100.0 1.5 200.0 3.0 :pre
|
|
|
|
pair_style buck/coul/cut 10.0
|
|
pair_style buck/coul/cut 10.0 8.0
|
|
pair_coeff * * 100.0 1.5 200.0
|
|
pair_coeff 1 1 100.0 1.5 200.0 9.0
|
|
pair_coeff 1 1 100.0 1.5 200.0 9.0 8.0 :pre
|
|
|
|
pair_style buck/coul/long 10.0
|
|
pair_style buck/coul/long 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:]
|
|
|
|
The {buck} style computes a Buckingham potential (exp/6 instead of
|
|
Lennard-Jones 12/6) given by
|
|
|
|
:c,image(Eqs/pair_buck.jpg)
|
|
|
|
where rho is an ionic-pair dependent length parameter, and Rc is the
|
|
cutoff.
|
|
|
|
The {buck/coul/cut} and {buck/coul/long} styles add a Coulombic term
|
|
as described for the "lj/cut"_pair_lj.html pair styles. For
|
|
{buck/coul/long}, an additional damping factor is applied to the
|
|
Coulombic term so it can be used in conjunction with the
|
|
"kspace_style"_kspace_style.html command and its {ewald} or {pppm}
|
|
option. The Coulombic cutoff specified for this style means that
|
|
pairwise interactions within this distance are computed directly;
|
|
interactions outside that distance are computed in reciprocal space.
|
|
|
|
If one cutoff is specified for the {born/coul/cut} and
|
|
{born/coulk/long} styles, it is used for both the A,C and Coulombic
|
|
terms. If two cutoffs are specified, the first is used as the cutoff
|
|
for the A,C terms, and the second is the cutoff for the Coulombic
|
|
term.
|
|
|
|
Note that these potentials are related to the "Born-Mayer-Huggins
|
|
potential"_pair_born.html.
|
|
|
|
The following coefficients must be defined for each pair of atoms
|
|
types via the "pair_coeff"_pair_coeff.html command as in the examples
|
|
above, or in the data file or restart files read by the
|
|
"read_data"_read_data.html or "read_restart"_read_restart.html
|
|
commands:
|
|
|
|
A (energy units)
|
|
rho (distance units)
|
|
C (energy-distance^6 units)
|
|
cutoff (distance units)
|
|
cutoff2 (distance units) :ul
|
|
|
|
The second coefficient, rho, must be greater than zero.
|
|
|
|
The latter 2 coefficients are optional. If not specified, the global
|
|
A,C and Coulombic cutoffs are used. If only one cutoff is specified,
|
|
it is used as the cutoff for both A,C and Coulombic interactions for
|
|
this type pair. If both coefficients are specified, they are used as
|
|
the A,C and Coulombic cutoffs for this type pair. You cannot specify
|
|
2 cutoffs for style {buck}, since it has no Coulombic terms.
|
|
|
|
For {buck/coul/long} only the LJ cutoff can be specified since a
|
|
Coulombic cutoff cannot be specified for an individual I,J type pair.
|
|
All type pairs use the same global Coulombic cutoff specified in the
|
|
pair_style command.
|
|
|
|
:line
|
|
|
|
Styles with a {cuda}, {gpu}, {omp}, or {opt} suffix are functionally
|
|
the same as the corresponding style without the suffix. They have
|
|
been optimized to run faster, depending on your available hardware,
|
|
as discussed in "this section"_Section_accelerate.html of the manual.
|
|
The accelerated styles take the same arguments and should produce the
|
|
same results, except for round-off and precision issues.
|
|
|
|
These accelerated styles are part of the USER-CUDA, GPU, USER-OMP and OPT
|
|
packages, respectively. They are only enabled if LAMMPS was built with
|
|
those packages. See the "Making LAMMPS"_Section_start.html#start_3
|
|
section for more info.
|
|
|
|
You can specify the accelerated styles explicitly in your input script
|
|
by including their suffix, or you can use the "-suffix command-line
|
|
switch"_Section_start.html#start_6 when you invoke LAMMPS, or you can
|
|
use the "suffix"_suffix.html command in your input script.
|
|
|
|
See "this section"_Section_accelerate.html of the manual for more
|
|
instructions on how to use the accelerated styles effectively.
|
|
|
|
:line
|
|
|
|
[Mixing, shift, table, tail correction, restart, rRESPA info]:
|
|
|
|
These pair styles do not support mixing. Thus, coefficients for all
|
|
I,J pairs must be specified explicitly.
|
|
|
|
These styles support the "pair_modify"_pair_modify.html shift option
|
|
for the energy of the exp() and 1/r^6 portion of the pair interaction.
|
|
|
|
The {buck/coul/long} pair style does not support the
|
|
"pair_modify"_pair_modify.html table option since a tabulation
|
|
capability has not yet been added to this potential.
|
|
|
|
These styles support the pair_modify tail option for adding long-range
|
|
tail corrections to energy and pressure for the A,C terms in the
|
|
pair interaction.
|
|
|
|
These styles write their information to "binary restart
|
|
files"_restart.html, so pair_style and pair_coeff commands do not need
|
|
to be specified in an input script that reads a restart file.
|
|
|
|
These styles can only be used via the {pair} keyword of the "run_style
|
|
respa"_run_style.html command. They do not support the {inner},
|
|
{middle}, {outer} keywords.
|
|
|
|
[Restrictions:]
|
|
|
|
The {buck/coul/long} style is part of the KSPACE package. It is only
|
|
enabled if LAMMPS was built with that package (which it is by
|
|
default). 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
|
|
|
|
[Default:] none
|