2006-09-22 00:22:34 +08:00
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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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<HR>
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<H3>write_restart command
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</H3>
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<P><B>Syntax:</B>
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</P>
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<PRE>write_restart file keyword value ...
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</PRE>
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<UL><LI>file = name of file to write restart information to
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<LI>zero or more keyword/value pairs may be appended
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<LI>keyword = <I>fileper</I> or <I>nfile</I>
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<PRE> <I>fileper</I> arg = Np
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Np = write one file for every this many processors
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<I>nfile</I> arg = Nf
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Nf = write this many files, one from each of Nf processors
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</PRE>
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2006-09-22 00:22:34 +08:00
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</UL>
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<P><B>Examples:</B>
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</P>
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<PRE>write_restart restart.equil
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write_restart poly.%.* nfile 10
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</PRE>
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<P><B>Description:</B>
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</P>
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<P>Write a binary restart file of the current state of the simulation.
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</P>
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<P>During a long simulation, the <A HREF = "restart.html">restart</A> command is
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typically used to output restart files periodically. The
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write_restart command is useful after a minimization or whenever you
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wish to write out a single current restart file.
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</P>
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<P>Similar to <A HREF = "dump.html">dump</A> files, the restart filename can contain
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two wild-card characters. If a "*" appears in the filename, it is
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replaced with the current timestep value. If a "%" character appears
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in the filename, then one file is written by each processor and the
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"%" character is replaced with the processor ID from 0 to P-1. An
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additional file with the "%" replaced by "base" is also written, which
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contains global information. For example, the files written for
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filename restart.% would be restart.base, restart.0, restart.1, ...
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restart.P-1. This creates smaller files and can be a fast mode of
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output and subsequent input on parallel machines that support parallel
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I/O. The optional <I>fileper</I> and <I>nfile</I> keywords discussed below can
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alter the number of files written.
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</P>
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<P>Restart files can be read by a <A HREF = "read_restart.html">read_restart</A>
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command to restart a simulation from a particular state. Because the
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file is binary (to enable exact restarts), it may not be readable on
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another machine. In this case, you can use the <A HREF = "Section_start.html#start_7">-r command-line
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switch</A> to convert a restart file to a data
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file.
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</P>
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2012-10-08 23:32:53 +08:00
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<P>IMPORTANT NOTE: Although the purpose of restart files is to enable
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restarting a simulation from where it left off, not all information
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about a simulation is stored in the file. For example, the list of
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fixes that were specified during the initial run is not stored, which
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means the new input script must specify any fixes you want to use.
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Even when restart information is stored in the file, as it is for some
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fixes, commands may need to be re-specified in the new input script,
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in order to re-use that information. See the
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<A HREF = "read_restart.html">read_restart</A> command for information about what is
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stored in a restart file.
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</P>
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<HR>
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<P>The optional <I>nfile</I> or <I>fileper</I> keywords can be used in conjunction
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with the "%" wildcard character in the specified restart file name.
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As explained above, the "%" character causes the restart file to be
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written in pieces, one piece for each of P processors. By default P =
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the number of processors the simulation is running on. The <I>nfile</I> or
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<I>fileper</I> keyword can be used to set P to a smaller value, which can
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be more efficient when running on a large number of processors.
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</P>
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<P>The <I>nfile</I> keyword sets P to the specified Nf value. For example, if
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Nf = 4, and the simulation is running on 100 processors, 4 files will
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be written, by processors 0,25,50,75. Each will collect information
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from itself and the next 24 processors and write it to a restart file.
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</P>
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<P>For the <I>fileper</I> keyword, the specified value of Np means write one
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file for every Np processors. For example, if Np = 4, every 4th
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processor (0,4,8,12,etc) will collect information from itself and the
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next 3 processors and write it to a restart file.
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</P>
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<HR>
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2006-09-22 00:22:34 +08:00
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<P><B>Restrictions:</B>
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</P>
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<P>This command requires inter-processor communication to migrate atoms
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before the restart file is written. This means that your system must
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be ready to perform a simulation before using this command (force
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fields setup, atom masses initialized, etc).
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</P>
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<P><B>Related commands:</B>
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</P>
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2013-04-04 01:06:31 +08:00
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<P><A HREF = "restart.html">restart</A>, <A HREF = "read_restart.html">read_restart</A>,
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<A HREF = "write_data.html">write_data</A>
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</P>
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<P><B>Default:</B> none
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</P>
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</HTML>
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