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<div class="section" id="pair-style-brownian-command">
<span id="index-0"></span><h1>pair_style brownian command</h1>
</div>
<div class="section" id="pair-style-brownian-omp-command">
<h1>pair_style brownian/omp command</h1>
</div>
<div class="section" id="pair-style-brownian-poly-command">
<h1>pair_style brownian/poly command</h1>
</div>
<div class="section" id="pair-style-brownian-poly-omp-command">
<h1>pair_style brownian/poly/omp command</h1>
<div class="section" id="syntax">
<h2>Syntax</h2>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">pair_style</span> <span class="n">style</span> <span class="n">mu</span> <span class="n">flaglog</span> <span class="n">flagfld</span> <span class="n">cutinner</span> <span class="n">cutoff</span> <span class="n">t_target</span> <span class="n">seed</span> <span class="n">flagHI</span> <span class="n">flagVF</span>
</pre></div>
</div>
<ul class="simple">
<li>style = <em>brownian</em> or <em>brownian/poly</em></li>
<li>mu = dynamic viscosity (dynamic viscosity units)</li>
<li>flaglog = 0/1 log terms in the lubrication approximation on/off</li>
<li>flagfld = 0/1 to include/exclude Fast Lubrication Dynamics effects</li>
<li>cutinner = inner cutoff distance (distance units)</li>
<li>cutoff = outer cutoff for interactions (distance units)</li>
<li>t_target = target temp of the system (temperature units)</li>
<li>seed = seed for the random number generator (positive integer)</li>
<li>flagHI (optional) = 0/1 to include/exclude 1/r hydrodynamic interactions</li>
<li>flagVF (optional) = 0/1 to include/exclude volume fraction corrections in the long-range isotropic terms</li>
</ul>
</div>
<div class="section" id="examples">
<h2>Examples</h2>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">pair_style</span> <span class="n">brownian</span> <span class="mf">1.5</span> <span class="mi">1</span> <span class="mi">1</span> <span class="mf">2.01</span> <span class="mf">2.5</span> <span class="mf">2.0</span> <span class="mi">5878567</span> <span class="p">(</span><span class="n">assuming</span> <span class="n">radius</span> <span class="o">=</span> <span class="mi">1</span><span class="p">)</span>
<span class="n">pair_coeff</span> <span class="mi">1</span> <span class="mi">1</span> <span class="mf">2.05</span> <span class="mf">2.8</span>
<span class="n">pair_coeff</span> <span class="o">*</span> <span class="o">*</span>
</pre></div>
</div>
</div>
<div class="section" id="description">
<h2>Description</h2>
<p>Styles <em>brownian</em> and <em>brownian/poly</em> compute Brownian forces and
torques on finite-size spherical 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 class="reference internal" href="pair_lubricate.html"><span class="doc">pair_style lubricate</span></a> or <a class="reference internal" href="pair_lubricateU.html"><span class="doc">pair_style lubricateU</span></a> commands to provide thermostatting
when dissipative lubrication forces are acting. Thus the parameters
<em>mu</em>, <em>flaglog</em>, <em>flagfld</em>, <em>cutinner</em>, and <em>cutoff</em> 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 <em>t_target</em> setting is used to specify the target temperature of
the system. The random number <em>seed</em> is used to generate random
numbers for the thermostatting procedure.</p>
<p>The <em>flagHI</em> and <em>flagVF</em> settings are optional. Neither should be
used, or both must be defined.</p>
<hr class="docutils" />
<p>The following coefficients must be defined for each pair of atoms
types via the <a class="reference internal" href="pair_coeff.html"><span class="doc">pair_coeff</span></a> command as in the examples
above, or in the data file or restart files read by the
<a class="reference internal" href="read_data.html"><span class="doc">read_data</span></a> or <a class="reference internal" href="read_restart.html"><span class="doc">read_restart</span></a>
commands, or by mixing as described below:</p>
<ul class="simple">
<li>cutinner (distance units)</li>
<li>cutoff (distance units)</li>
</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 class="docutils" />
<p>Styles with a <em>gpu</em>, <em>intel</em>, <em>kk</em>, <em>omp</em>, or <em>opt</em> 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 class="reference internal" href="Section_accelerate.html"><span class="doc">this section</span></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 GPU, USER-INTEL, KOKKOS,
USER-OMP and OPT packages, respectively. They are only enabled if
LAMMPS was built with those packages. See the <a class="reference internal" href="Section_start.html#start-3"><span class="std std-ref">Making LAMMPS</span></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 class="reference internal" href="Section_start.html#start-7"><span class="std std-ref">-suffix command-line switch</span></a> when you invoke LAMMPS, or you can
use the <a class="reference internal" href="suffix.html"><span class="doc">suffix</span></a> command in your input script.</p>
<p>See <a class="reference internal" href="Section_accelerate.html"><span class="doc">this section</span></a> of the manual for more
instructions on how to use the accelerated styles effectively.</p>
<hr class="docutils" />
<p><strong>Mixing, shift, table, tail correction, restart, rRESPA info</strong>:</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 <em>geometric</em>. See
the &#8220;pair_modify&#8221; command for details.</p>
<p>This pair style does not support the <a class="reference internal" href="pair_modify.html"><span class="doc">pair_modify</span></a>
shift option for the energy of the pair interaction.</p>
<p>The <a class="reference internal" href="pair_modify.html"><span class="doc">pair_modify</span></a> table option is not relevant
for this pair style.</p>
<p>This pair style does not support the <a class="reference internal" href="pair_modify.html"><span class="doc">pair_modify</span></a>
tail option for adding long-range tail corrections to energy and
pressure.</p>
<p>This pair style writes its information to <a class="reference internal" href="restart.html"><span class="doc">binary restart files</span></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 <em>pair</em> keyword of the
<a class="reference internal" href="run_style.html"><span class="doc">run_style respa</span></a> command. It does not support the
<em>inner</em>, <em>middle</em>, <em>outer</em> keywords.</p>
</div>
<hr class="docutils" />
<div class="section" id="restrictions">
<h2>Restrictions</h2>
<p>These styles are part of the COLLOID package. They are only enabled
if LAMMPS was built with that package. See the <span class="xref std std-ref">Making LAMMPS</span> 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>
</div>
<div class="section" id="related-commands">
<h2>Related commands</h2>
<p><a class="reference internal" href="pair_coeff.html"><span class="doc">pair_coeff</span></a>, <a class="reference internal" href="pair_lubricate.html"><span class="doc">pair_style lubricate</span></a>, <a class="reference internal" href="pair_lubricateU.html"><span class="doc">pair_style lubricateU</span></a></p>
</div>
<div class="section" id="default">
<h2>Default</h2>
<p>The default settings for the optional args are flagHI = 1 and flagVF =
1.</p>
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