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>fix freeze command
|
|
|
|
|
</H3>
|
2011-06-09 05:46:03 +08:00
|
|
|
<H3>fix freeze/cuda command
|
|
|
|
|
</H3>
|
2006-09-22 00:22:34 +08:00
|
|
|
<P><B>Syntax:</B>
|
|
|
|
|
</P>
|
|
|
|
|
<PRE>fix ID group-ID freeze
|
|
|
|
|
</PRE>
|
|
|
|
|
<UL><LI>ID, group-ID are documented in <A HREF = "fix.html">fix</A> command
|
|
|
|
|
<LI>freeze = style name of this fix command
|
|
|
|
|
</UL>
|
|
|
|
|
<P><B>Examples:</B>
|
|
|
|
|
</P>
|
|
|
|
|
<PRE>fix 2 bottom freeze
|
|
|
|
|
</PRE>
|
|
|
|
|
<P><B>Description:</B>
|
|
|
|
|
</P>
|
|
|
|
|
<P>Zero out the force and torque on a granular particle. This is useful
|
2009-06-23 04:49:14 +08:00
|
|
|
for preventing certain particles from moving in a simulation. The
|
|
|
|
|
<A HREF = "pair_gran.html">granular pair styles</A> also detect if this fix has been
|
|
|
|
|
defined and compute interactions between frozen and non-frozen
|
|
|
|
|
particles appropriately, as if the frozen particle has infinite mass.
|
2006-09-22 00:22:34 +08:00
|
|
|
</P>
|
2011-06-09 05:46:03 +08:00
|
|
|
<HR>
|
|
|
|
|
|
|
|
|
|
<P>Styles with a <I>cuda</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
|
2011-12-14 04:35:35 +08:00
|
|
|
<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 05:46:03 +08:00
|
|
|
</P>
|
2011-08-27 02:53:00 +08:00
|
|
|
<P>These accelerated styles are part of the USER-CUDA package. They are
|
|
|
|
|
only enabled if LAMMPS was built with that package. See the <A HREF = "Section_start.html#start_3">Making
|
|
|
|
|
LAMMPS</A> section for more info.
|
2011-06-09 05:46:03 +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 05:46:03 +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 05:46:03 +08:00
|
|
|
</P>
|
|
|
|
|
<HR>
|
|
|
|
|
|
2007-10-11 06:28:11 +08:00
|
|
|
<P><B>Restart, fix_modify, output, run start/stop, minimize info:</B>
|
2007-06-26 08:03:39 +08:00
|
|
|
</P>
|
|
|
|
|
<P>No information about this fix is written to <A HREF = "restart.html">binary restart
|
|
|
|
|
files</A>. None of the <A HREF = "fix_modify.html">fix_modify</A> options
|
2009-06-23 04:49:14 +08:00
|
|
|
are relevant to this fix.
|
|
|
|
|
</P>
|
2010-04-03 00:51:06 +08:00
|
|
|
<P>This fix computes a global 3-vector of forces, which can be accessed
|
2011-08-26 01:01:01 +08:00
|
|
|
by various <A HREF = "Section_howto.html#howto_15">output commands</A>. This is the
|
2010-04-03 00:51:06 +08:00
|
|
|
total force on the group of atoms before the forces on individual
|
|
|
|
|
atoms are changed by the fix. The vector values calculated by this
|
|
|
|
|
fix are "extensive".
|
2009-06-23 04:49:14 +08:00
|
|
|
</P>
|
|
|
|
|
<P>No parameter of this fix can be used with the <I>start/stop</I> keywords of
|
|
|
|
|
the <A HREF = "run.html">run</A> command. This fix is not invoked during <A HREF = "minimize.html">energy
|
|
|
|
|
minimization</A>.
|
2007-06-26 08:03:39 +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>This fix is part of the GRANULAR package. It is only enabled if
|
2011-08-26 00:46:23 +08:00
|
|
|
LAMMPS was built with that package. See the <A HREF = "Section_start.html#start_3">Making
|
2007-06-26 08:03:39 +08:00
|
|
|
LAMMPS</A> section for more info.
|
2006-09-22 00:22:34 +08:00
|
|
|
</P>
|
|
|
|
|
<P>There can only be a single freeze fix defined. This is because other
|
2009-06-23 04:49:14 +08:00
|
|
|
the <A HREF = "pair_gran.html">granular pair styles</A> treat frozen particles
|
|
|
|
|
differently and need to be able to reference a single group to which
|
|
|
|
|
this fix is applied.
|
2006-09-22 00:22:34 +08:00
|
|
|
</P>
|
|
|
|
|
<P><B>Related commands:</B> none
|
|
|
|
|
</P>
|
2011-04-14 05:39:34 +08:00
|
|
|
<P><A HREF = "atom_style.html">atom_style sphere</A>
|
2006-09-22 00:22:34 +08:00
|
|
|
</P>
|
|
|
|
|
<P><B>Default:</B> none
|
|
|
|
|
</P>
|
|
|
|
|
</HTML>
|
