2006-09-22 00:22:34 +08:00
|
|
|
<HTML>
|
|
|
|
|
<CENTER><A HREF = "http://lammps.sandia.gov">LAMMPS WWW Site</A> - <A HREF = "Manual.html">LAMMPS Documentation</A> - <A HREF = "Section_commands.html#comm">LAMMPS Commands</A>
|
|
|
|
|
</CENTER>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<HR>
|
|
|
|
|
|
|
|
|
|
<H3>pair_style lj/class2 command
|
|
|
|
|
</H3>
|
2011-06-09 05:46:03 +08:00
|
|
|
<H3>pair_style lj/class2/cuda command
|
|
|
|
|
</H3>
|
2011-06-09 04:56:17 +08:00
|
|
|
<H3>pair_style lj/class2/gpu command
|
|
|
|
|
</H3>
|
2011-10-07 01:32:51 +08:00
|
|
|
<H3>pair_style lj/class2/omp command
|
|
|
|
|
</H3>
|
2006-09-22 00:22:34 +08:00
|
|
|
<H3>pair_style lj/class2/coul/cut command
|
|
|
|
|
</H3>
|
2011-06-09 05:46:03 +08:00
|
|
|
<H3>pair_style lj/class2/coul/cut/cuda command
|
|
|
|
|
</H3>
|
2011-10-07 01:32:51 +08:00
|
|
|
<H3>pair_style lj/class2/coul/cut/omp command
|
|
|
|
|
</H3>
|
2006-09-22 00:22:34 +08:00
|
|
|
<H3>pair_style lj/class2/coul/long command
|
|
|
|
|
</H3>
|
2011-06-09 05:46:03 +08:00
|
|
|
<H3>pair_style lj/class2/coul/long/cuda command
|
|
|
|
|
</H3>
|
2011-06-09 04:56:17 +08:00
|
|
|
<H3>pair_style lj/class2/coul/long/gpu command
|
|
|
|
|
</H3>
|
2011-10-07 01:32:51 +08:00
|
|
|
<H3>pair_style lj/class2/coul/long/omp command
|
|
|
|
|
</H3>
|
2006-09-22 00:22:34 +08:00
|
|
|
<P><B>Syntax:</B>
|
|
|
|
|
</P>
|
|
|
|
|
<PRE>pair_style style args
|
|
|
|
|
</PRE>
|
2011-06-09 05:26:06 +08:00
|
|
|
<UL><LI>style = <I>lj/class2</I> or <I>lj/class2/coul/cut</I> or <I>lj/class2/coul/long</I>
|
2006-09-22 00:22:34 +08:00
|
|
|
<LI>args = list of arguments for a particular style
|
|
|
|
|
</UL>
|
|
|
|
|
<PRE> <I>lj/class2</I> args = cutoff
|
|
|
|
|
cutoff = global cutoff for class 2 interactions (distance units)
|
|
|
|
|
<I>lj/class2/coul/cut</I> args = cutoff (cutoff2)
|
|
|
|
|
cutoff = global cutoff for class 2 (and Coulombic if only 1 arg) (distance units)
|
|
|
|
|
cutoff2 = global cutoff for Coulombic (optional) (distance units)
|
|
|
|
|
<I>lj/class2/coul/long</I> args = cutoff (cutoff2)
|
|
|
|
|
cutoff = global cutoff for class 2 (and Coulombic if only 1 arg) (distance units)
|
|
|
|
|
cutoff2 = global cutoff for Coulombic (optional) (distance units)
|
|
|
|
|
</PRE>
|
|
|
|
|
<P><B>Examples:</B>
|
|
|
|
|
</P>
|
|
|
|
|
<PRE>pair_style lj/class2 10.0
|
|
|
|
|
pair_coeff * * 100.0 2.5
|
|
|
|
|
pair_coeff 1 2* 100.0 2.5 9.0
|
|
|
|
|
</PRE>
|
|
|
|
|
<PRE>pair_style lj/class2/coul/cut 10.0
|
|
|
|
|
pair_style lj/class2/coul/cut 10.0 8.0
|
|
|
|
|
pair_coeff * * 100.0 3.0
|
|
|
|
|
pair_coeff 1 1 100.0 3.5 9.0
|
|
|
|
|
pair_coeff 1 1 100.0 3.5 9.0 9.0
|
|
|
|
|
</PRE>
|
|
|
|
|
<PRE>pair_style lj/class2/coul/long 10.0
|
|
|
|
|
pair_style lj/class2/coul/long 10.0 8.0
|
|
|
|
|
pair_coeff * * 100.0 3.0
|
|
|
|
|
pair_coeff 1 1 100.0 3.5 9.0
|
|
|
|
|
</PRE>
|
|
|
|
|
<P><B>Description:</B>
|
|
|
|
|
</P>
|
|
|
|
|
<P>The <I>lj/class2</I> styles compute a 6/9 Lennard-Jones potential given by
|
|
|
|
|
</P>
|
|
|
|
|
<CENTER><IMG SRC = "Eqs/pair_class2.jpg">
|
|
|
|
|
</CENTER>
|
|
|
|
|
<P>Rc is the cutoff.
|
|
|
|
|
</P>
|
|
|
|
|
<P>The <I>lj/class2/coul/cut</I> and <I>lj/class2/coul/long</I> styles add a
|
2012-10-03 07:18:29 +08:00
|
|
|
Coulombic term as described for the <A HREF = "pair_lj.html">lj/cut</A> pair styles.
|
2006-09-22 00:22:34 +08:00
|
|
|
</P>
|
2006-09-28 03:12:31 +08:00
|
|
|
<P>See <A HREF = "#Sun">(Sun)</A> for a description of the COMPASS class2 force field.
|
|
|
|
|
</P>
|
2006-09-22 00:22:34 +08:00
|
|
|
<P>The following coefficients must be defined for each pair of atoms
|
|
|
|
|
types via the <A HREF = "pair_coeff.html">pair_coeff</A> command as in the examples
|
|
|
|
|
above, or in the data file or restart files read by the
|
|
|
|
|
<A HREF = "read_data.html">read_data</A> or <A HREF = "read_restart.html">read_restart</A>
|
2007-06-25 22:36:36 +08:00
|
|
|
commands, or by mixing as described below:
|
2006-09-22 00:22:34 +08:00
|
|
|
</P>
|
|
|
|
|
<UL><LI>epsilon (energy units)
|
|
|
|
|
<LI>sigma (distance units)
|
|
|
|
|
<LI>cutoff1 (distance units)
|
|
|
|
|
<LI>cutoff2 (distance units)
|
|
|
|
|
</UL>
|
|
|
|
|
<P>The latter 2 coefficients are optional. If not specified, the global
|
|
|
|
|
class 2 and Coulombic cutoffs are used. If only one cutoff is
|
|
|
|
|
specified, it is used as the cutoff for both class 2 and Coulombic
|
|
|
|
|
interactions for this type pair. If both coefficients are specified,
|
|
|
|
|
they are used as the class 2 and Coulombic cutoffs for this type pair.
|
|
|
|
|
You cannot specify 2 cutoffs for style <I>lj/class2</I>, since it has no
|
|
|
|
|
Coulombic terms.
|
|
|
|
|
</P>
|
|
|
|
|
<P>For <I>lj/class2/coul/long</I> only the class 2 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.
|
|
|
|
|
</P>
|
2011-06-09 05:46:03 +08:00
|
|
|
<HR>
|
|
|
|
|
|
2007-04-20 07:25:27 +08:00
|
|
|
<P>If the pair_coeff command is not used to define coefficients for a
|
|
|
|
|
particular I != J type pair, the mixing rule for epsilon and sigma for
|
|
|
|
|
all class2 potentials is to use the <I>sixthpower</I> formulas documented
|
|
|
|
|
by the <A HREF = "pair_modify.html">pair_modify</A> command. The <A HREF = "pair_modify.html">pair_modify
|
|
|
|
|
mix</A> setting is thus ignored for class2 potentials
|
|
|
|
|
for epsilon and sigma. However it is still followed for mixing the
|
|
|
|
|
cutoff distance.
|
|
|
|
|
</P>
|
2011-06-09 04:56:17 +08:00
|
|
|
<HR>
|
|
|
|
|
|
2014-08-15 00:30:25 +08:00
|
|
|
<P>Styles with a <I>cuda</I>, <I>gpu</I>, <I>intel</I>, <I>kk</I>, <I>omp</I>, or <I>opt</I> 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 <A HREF = "Section_accelerate.html">Section_accelerate</A>
|
|
|
|
|
of the manual. The accelerated styles take the same arguments and
|
|
|
|
|
should produce the same results, except for round-off and precision
|
|
|
|
|
issues.
|
2011-06-09 05:26:06 +08:00
|
|
|
</P>
|
2014-08-15 00:30:25 +08:00
|
|
|
<P>These accelerated styles are part of the USER-CUDA, GPU, USER-INTEL,
|
|
|
|
|
KOKKOS, USER-OMP and OPT packages, respectively. They are only
|
|
|
|
|
enabled if LAMMPS was built with those packages. See the <A HREF = "Section_start.html#start_3">Making
|
|
|
|
|
LAMMPS</A> section for more info.
|
2011-06-09 05:26:06 +08:00
|
|
|
</P>
|
|
|
|
|
<P>You can specify the accelerated styles explicitly in your input script
|
2012-01-28 07:39:14 +08:00
|
|
|
by including their suffix, or you can use the <A HREF = "Section_start.html#start_7">-suffix command-line
|
2011-08-26 00:46:23 +08:00
|
|
|
switch</A> when you invoke LAMMPS, or you can
|
|
|
|
|
use the <A HREF = "suffix.html">suffix</A> command in your input script.
|
2011-06-09 05:26:06 +08:00
|
|
|
</P>
|
2011-12-14 04:35:35 +08:00
|
|
|
<P>See <A HREF = "Section_accelerate.html">Section_accelerate</A> of the manual for
|
|
|
|
|
more instructions on how to use the accelerated styles effectively.
|
2011-06-09 04:56:17 +08:00
|
|
|
</P>
|
2011-10-07 01:32:51 +08:00
|
|
|
<HR>
|
|
|
|
|
|
2008-01-22 02:12:34 +08:00
|
|
|
<P><B>Mixing, shift, table, tail correction, restart, rRESPA info</B>:
|
2007-06-25 22:36:36 +08:00
|
|
|
</P>
|
|
|
|
|
<P>For atom type pairs I,J and I != J, the epsilon and sigma coefficients
|
|
|
|
|
and cutoff distance for all of the lj/class2 pair styles can be mixed.
|
|
|
|
|
Epsilon and sigma are always mixed with the value <I>sixthpower</I>. The
|
|
|
|
|
cutoff distance is mixed by whatever option is set by the pair_modify
|
|
|
|
|
command (default = geometric). See the "pair_modify" command for
|
|
|
|
|
details.
|
|
|
|
|
</P>
|
|
|
|
|
<P>All of the lj/class2 pair styles support the
|
|
|
|
|
<A HREF = "pair_modify.html">pair_modify</A> shift option for the energy of the
|
|
|
|
|
Lennard-Jones portion of the pair interaction.
|
|
|
|
|
</P>
|
|
|
|
|
<P>The <I>lj/class2/coul/long</I> pair style does not support the
|
|
|
|
|
<A HREF = "pair_modify.html">pair_modify</A> table option since a tabulation
|
|
|
|
|
capability has not yet been added to this potential.
|
|
|
|
|
</P>
|
|
|
|
|
<P>All of the lj/class2 pair styles support the
|
|
|
|
|
<A HREF = "pair_modify.html">pair_modify</A> tail option for adding a long-range
|
|
|
|
|
tail correction to the energy and pressure of the Lennard-Jones
|
|
|
|
|
portion of the pair interaction.
|
|
|
|
|
</P>
|
|
|
|
|
<P>All of the lj/class2 pair styles write their information to <A HREF = "restart.html">binary
|
|
|
|
|
restart files</A>, so pair_style and pair_coeff commands do
|
|
|
|
|
not need to be specified in an input script that reads a restart file.
|
|
|
|
|
</P>
|
2007-10-04 08:21:14 +08:00
|
|
|
<P>All of the lj/class2 pair styles can only be used via the <I>pair</I>
|
|
|
|
|
keyword of the <A HREF = "run_style.html">run_style respa</A> command. They do not
|
2007-10-12 07:09:49 +08:00
|
|
|
support the <I>inner</I>, <I>middle</I>, <I>outer</I> keywords.
|
2007-10-04 08:21:14 +08:00
|
|
|
</P>
|
2006-09-22 00:22:34 +08:00
|
|
|
<P><B>Restrictions:</B>
|
|
|
|
|
</P>
|
2011-08-27 02:53:00 +08:00
|
|
|
<P>These styles are part of the CLASS2 package. They are only enabled if
|
|
|
|
|
LAMMPS was built with that package. See the <A HREF = "Section_start.html#start_3">Making
|
2011-06-09 05:26:06 +08:00
|
|
|
LAMMPS</A> section for more info.
|
2006-09-22 00:22:34 +08:00
|
|
|
</P>
|
|
|
|
|
<P><B>Related commands:</B>
|
|
|
|
|
</P>
|
|
|
|
|
<P><A HREF = "pair_coeff.html">pair_coeff</A>
|
|
|
|
|
</P>
|
|
|
|
|
<P><B>Default:</B> none
|
|
|
|
|
</P>
|
2006-09-28 03:12:31 +08:00
|
|
|
<HR>
|
|
|
|
|
|
|
|
|
|
<A NAME = "Sun"></A>
|
|
|
|
|
|
|
|
|
|
<P><B>(Sun)</B> Sun, J Phys Chem B 102, 7338-7364 (1998).
|
|
|
|
|
</P>
|
2006-09-22 00:22:34 +08:00
|
|
|
</HTML>
|
