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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>restart command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>restart 0
restart N root
restart N file1 file2
</PRE>
<UL><LI>N = write a restart file every this many timesteps
<LI>root = filename to which timestep # is appended
<LI>file1,file2 = two full filenames, toggle between them when writing file
</UL>
<P><B>Examples:</B>
</P>
<PRE>restart 0
restart 1000 poly.restart
restart 1000 restart.*.equil
restart 10000 poly.%.1 poly.%.2
</PRE>
<P><B>Description:</B>
</P>
<P>Write out a binary restart file every so many timesteps as a run
proceeds. A value of 0 means do not write out restart files. Using
one filename as an argument will create a series of filenames which
include the timestep in the filename. Using two filenames will
produce only 2 restart files. LAMMPS will toggle between the 2 names
as it writes successive restart files.
</P>
<P>Similar to <A HREF = "dump.html">dump</A> files, the restart filename(s) can contain
two wild-card characters. If a "*" appears in the filename, it is
replaced with the current timestep value. This is only recognized
when a single filename is used (not when toggling back and forth).
Thus, the 3rd example above creates restart files as follows:
restart.1000.equil, restart.2000.equil, etc. If a single filename is
used with no "*", then the timestep value is appended. E.g. the 2nd
example above creates restart files as follows: poly.restart.1000,
poly.restart.2000, etc.
</P>
<P>If a "%" character appears in the restart filename(s), then one file
is written for each processor and the "%" character is replaced with
the processor ID from 0 to P-1. An additional file with the "%"
replaced by "base" is also written, which contains global information.
For example, the files written on step 1000 for filename restart.%
would be restart.base.1000, restart.0.1000, restart.1.1000, ...,
restart.P-1.1000. This creates smaller files and can be a fast mode
of output on parallel machines that support parallel I/O for output.
</P>
<P>Restart files are written on timesteps that are a multiple of N but
not on the first timestep of a run or minimization. A restart file is
not written on the last timestep of a run unless it is a multiple of
N. A restart file is written on the last timestep of a minimization
if N > 0 and the minimization converges.
</P>
<P>See the <A HREF = "read_restart.html">read_restart</A> command for information about
what is stored in a restart file.
</P>
<P>Restart files can be read by a <A HREF = "read_restart.html">read_restart</A>
command to restart a simulation from a particular state. Because the
file is binary (to enable exact restarts), it may not be readable on
another machine. In this case, the <A HREF = "Section_tools.html#restart">restart2data
program</A> in the tools directory can be used
to convert a restart file to an ASCII data file. Both the
read_restart commmand and restart2data tool can read in a restart file
that was written with the "%" character so that multiple files were
created.
</P>
<P><B>Restrictions:</B> none
</P>
<P><B>Related commands:</B>
</P>
<P><A HREF = "write_restart.html">write_restart</A>, <A HREF = "read_restart.html">read_restart</A>
</P>
<P><B>Default:</B>
</P>
<PRE>restart 0
</PRE>
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