"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c

:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Commands_all.html)

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pair_style lj/expand command :h3
pair_style lj/expand/gpu command :h3
pair_style lj/expand/kk command :h3
pair_style lj/expand/omp command :h3
pair_style lj/expand/coul/long command :h3
pair_style lj/expand/coul/long/gpu command :h3

[Syntax:]

pair_style lj/expand cutoff :pre

cutoff = global cutoff for lj/expand interactions (distance units) :ul

[Examples:]

pair_style lj/expand 2.5
pair_coeff * * 1.0 1.0 0.5
pair_coeff 1 1 1.0 1.0 -0.2 2.0 :pre

pair_style lj/expand/coul/long 2.5
pair_style lj/expand/coul/long 2.5 4.0
pair_coeff * * 1.0 1.0 0.5
pair_coeff 1 1 1.0 1.0 -0.2 3.0 :pre

[Description:]

Style {lj/expand} computes a LJ interaction with a distance shifted by
delta which can be useful when particles are of different sizes, since
it is different that using different sigma values in a standard LJ
formula:

:c,image(Eqs/pair_lj_expand.jpg)

Rc is the cutoff which does not include the delta distance.  I.e. the
actual force cutoff is the sum of cutoff + delta.

For all of the {lj/expand} pair styles, 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, or by mixing as
described below:

epsilon (energy units)
sigma (distance units)
delta (distance units)
cutoff (distance units) :ul

The delta values can be positive or negative.  The last coefficient is
optional.  If not specified, the global LJ cutoff is used.

For {lj/expand/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.

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Styles with a {gpu}, {intel}, {kk}, {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 on the "Speed packages"_Speed_packages.html doc
page.  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 GPU, USER-INTEL, KOKKOS,
USER-OMP and OPT packages, respectively.  They are only enabled if
LAMMPS was built with those packages.  See the "Build
package"_Build_package.html doc page 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"_Run_options.html when you invoke LAMMPS, or you can use the
"suffix"_suffix.html command in your input script.

See the "Speed packages"_Speed_packages.html doc page for more
instructions on how to use the accelerated styles effectively.

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[Mixing, shift, table, tail correction, restart, rRESPA info]:

For atom type pairs I,J and I != J, the epsilon, sigma, and shift
coefficients and cutoff distance for this pair style can be mixed.
Shift is always mixed via an {arithmetic} rule.  The other
coefficients are mixed according to the pair_modify mix value.  The
default mix value is {geometric}.  See the "pair_modify" command for
details.

This pair style supports the "pair_modify"_pair_modify.html shift
option for the energy of the pair interaction.

The "pair_modify"_pair_modify.html table option is not relevant
for this pair style.

This pair style supports the "pair_modify"_pair_modify.html tail
option for adding a long-range tail correction to the energy and
pressure of the pair interaction.

This pair style writes its 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.

This pair style can only be used via the {pair} keyword of the
"run_style respa"_run_style.html command.  It does not support the
{inner}, {middle}, {outer} keywords.

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[Restrictions:] none

[Related commands:]

"pair_coeff"_pair_coeff.html

[Default:] none
