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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>
</CENTER>
<HR>
<H3>fix shardlow command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>fix ID group-ID shardlow
</PRE>
<UL><LI>ID, group-ID are documented in <A HREF = "fix.html">fix</A> command
<LI>shardlow = style name of this fix command
</UL>
<P><B>Examples:</B>
</P>
<PRE>fix 1 all shardlow
</PRE>
<P><B>Description:</B>
</P>
<P>Specifies that the Shardlow splitting algorithm (SSA) is to be used to
integrate the DPD equations of motion. The SSA splits the integration
into a stochastic and deterministic integration step. The fix
<I>shardlow</I> performs the stochastic integration step and must be used
in conjunction with a deterministic integrator (e.g. <A HREF = "fix_nve.html">fix
nve</A> or <A HREF = "fix_nph.html">fix nph</A>). The stochastic
integration of the dissipative and random forces is performed prior to
the deterministic integration of the conservative force. Further
details regarding the method are provided in <A HREF = "#Lisal">(Lisal)</A> and
<A HREF = "#Larentzos">(Larentzos)</A>.
</P>
<P>The fix <I>shardlow</I> must be used with the <A HREF = "pair_style.html">pair_style
dpd/fdt</A> or <A HREF = "pair_style.html">pair_style
dpd/fdt/energy</A> command to properly initialize the
fluctuation-dissipation theorem parameter(s) sigma (and kappa, if
necessary).
</P>
<P>Note that numerous variants of DPD can be specified by choosing an
appropriate combination of the integrator and <A HREF = "pair_style.html">pair_style
dpd/fdt</A> command. DPD under isothermal conditions can
be specified by using fix <I>shardlow</I>, fix <I>nve</I> and pair_style
<I>dpd/fdt</I>. DPD under isoenergetic conditions can be specified by
using fix <I>shardlow</I>, fix <I>nve</I> and pair_style <I>dpd/fdt/energy</I>. DPD
under isobaric conditions can be specified by using fix shardlow, fix
<I>nph</I> and pair_style <I>dpd/fdt</I>. DPD under isoenthalpic conditions can
be specified by using fix shardlow, fix <I>nph</I> and pair_style
<I>dpd/fdt/energy</I>. Examples of each DPD variant are provided in the
examples/USER/dpd directory.
</P>
<HR>
<P><B>Restrictions:</B>
</P>
<P>This fix is only available if LAMMPS is built with the USER-DPD
package. See the <A HREF = "Section_start.html#start_3">Making LAMMPS</A> section
for more info.
</P>
<P>This fix is currently limited to orthogonal simulation cell
geometries.
</P>
<P>This fix must be used with an additional fix that specifies time
integration, e.g. <A HREF = "fix_nve.html">fix nve</A> or <A HREF = "fix_nh.html">fix nph</A>.
</P>
<P>The Shardlow splitting algorithm requires the sizes of the sub-domain
lengths to be larger than twice the cutoff+skin. Generally, the
domain decomposition is dependant on the number of processors
requested.
</P>
<P><B>Related commands:</B>
</P>
<P><A HREF = "pair_dpd_fdt.html">pair_style dpd/fdt</A>, <A HREF = "fix_eos_cv.html">fix eos/cv</A>
</P>
<P><B>Default:</B> none
</P>
<HR>
<A NAME = "Lisal"></A>
<P><B>(Lisal)</B> M. Lisal, J.K. Brennan, J. Bonet Avalos, "Dissipative
particle dynamics as isothermal, isobaric, isoenergetic, and
isoenthalpic conditions using Shardlow-like splitting algorithms.",
J. Chem. Phys., 135, 204105 (2011).
</P>
<A NAME = "Larentzos"></A>
<P><B>(Larentzos)</B> J.P. Larentzos, J.K. Brennan, J.D. Moore, M. Lisal and
W.D. Mattson, "Parallel Implementation of Isothermal and Isoenergetic
Dissipative Particle Dynamics Using Shardlow-Like Splitting
Algorithms", Comput. Phys. Commun., 185, 1987-1998 (2014).
</P>
<A NAME = "Larentzos"></A>
<P><B>(Larentzos)</B> J.P. Larentzos, J.K. Brennan, J.D. Moore, and
W.D. Mattson, "LAMMPS Implementation of Constant Energy Dissipative
Particle Dynamics (DPD-E)", ARL-TR-6863, U.S. Army Research
Laboratory, Aberdeen Proving Ground, MD (2014).
</P>
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