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<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>
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<H3>pair_style brownian command
</H3>
<H3>pair_style brownian/omp command
</H3>
<H3>pair_style brownian/poly command
</H3>
<H3>pair_style brownian/poly/omp command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>pair_style style mu flaglog flagfld cutinner cutoff t_target seed flagHI flagVF
</PRE>
<UL><LI>style = <I>brownian</I> or <I>brownian/poly</I>
<LI>mu = dynamic viscosity (dynamic viscosity units)
<LI>flaglog = 0/1 log terms in the lubrication approximation on/off
<LI>flagfld = 0/1 to include/exclude Fast Lubrication Dynamics effects
<LI>cutinner = inner cutoff distance (distance units)
<LI>cutoff = outer cutoff for interactions (distance units)
<LI>t_target = target temp of the system (temperature units)
<LI>seed = seed for the random number generator (positive integer)
<LI>flagHI (optional) = 0/1 to include/exclude 1/r hydrodynamic interactions
<LI>flagVF (optional) = 0/1 to include/exclude volume fraction corrections in the long-range isotropic terms
</UL>
<P><B>Examples:</B>
</P>
<PRE>pair_style brownian 1.5 1 1 2.01 2.5 2.0 5878567 (assuming radius = 1)
pair_coeff 1 1 2.05 2.8
pair_coeff * *
</PRE>
<P><B>Description:</B>
</P>
<P>Styles <I>brownian</I> and <I>brownain/poly</I> compute Brownian forces and
torques on finite-size particles. The former requires monodisperse
spherical particles; the latter allows for polydisperse spherical
particles.
</P>
<P>These pair styles are designed to be used with either the <A HREF = "pair_lubricate.html">pair_style
lubricate</A> or <A HREF = "pair_lubricateU.html">pair_style
lubricateU</A> commands to provide thermostatting
when dissipative lubrication forces are acting. Thus the parameters
<I>mu</I>, <I>flaglog</I>, <I>flagfld</I>, <I>cutinner</I>, and <I>cutoff</I> should be
specified consistent with the settings in the lubrication pair styles.
For details, refer to either of the lubrication pair styles.
</P>
<P>The <I>t_target</I> setting is used to specify the target temperature of
the system. The random number <I>seed</I> is used to generate random
numbers for the thermostatting procedure.
</P>
<P>The <I>flagHI</I> and <I>flagVF</I> settings are optional. Neither should be
used, or both must be defined.
</P>
<HR>
<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>
commands, or by mixing as described below:
</P>
<UL><LI>cutinner (distance units)
<LI>cutoff (distance units)
</UL>
<P>The two coefficients are optional. If neither is specified, the two
cutoffs specified in the pair_style command are used. Otherwise both
must be specified.
</P>
<HR>
<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">this section</A> of
the manual. The accelerated styles take the same arguments and should
produce the same results, except for round-off and precision issues.
</P>
<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.
</P>
<P>You can specify the accelerated styles explicitly in your input script
by including their suffix, or you can use the <A HREF = "Section_start.html#start_7">-suffix command-line
switch</A> when you invoke LAMMPS, or you can
use the <A HREF = "suffix.html">suffix</A> command in your input script.
</P>
<P>See <A HREF = "Section_accelerate.html">this section</A> of the manual for more
instructions on how to use the accelerated styles effectively.
</P>
<HR>
<P><B>Mixing, shift, table, tail correction, restart, rRESPA info</B>:
</P>
<P>For atom type pairs I,J and I != J, the two cutoff distances for this
pair style can be mixed. The default mix value is <I>geometric</I>. See
the "pair_modify" command for details.
</P>
<P>This pair style does not support the <A HREF = "pair_modify.html">pair_modify</A>
shift option for the energy of the pair interaction.
</P>
<P>The <A HREF = "pair_modify.html">pair_modify</A> table option is not relevant
for this pair style.
</P>
<P>This pair style does not support the <A HREF = "pair_modify.html">pair_modify</A>
tail option for adding long-range tail corrections to energy and
pressure.
</P>
<P>This pair style writes its 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>
<P>This pair style can only be used via the <I>pair</I> keyword of the
<A HREF = "run_style.html">run_style respa</A> command. It does not support the
<I>inner</I>, <I>middle</I>, <I>outer</I> keywords.
</P>
<HR>
<P><B>Restrictions:</B>
</P>
<P>These styles are part of the FLD package. They are only enabled if
LAMMPS was built with that package. See the <A HREF = "Section_start.html#2_3">Making
LAMMPS</A> section for more info.
</P>
<P>Only spherical monodisperse particles are allowed for pair_style
brownian.
</P>
<P>Only spherical particles are allowed for pair_style brownian/poly.
</P>
<P><B>Related commands:</B>
</P>
<P><A HREF = "pair_coeff.html">pair_coeff</A>, <A HREF = "pair_lubricate.html">pair_style
lubricate</A>, <A HREF = "pair_lubricateU.html">pair_style
lubricateU</A>
</P>
<P><B>Default:</B>
</P>
<P>The default settings for the optional args are flagHI = 1 and flagVF =
1.
</P>
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