forked from lijiext/lammps
86 lines
3.0 KiB
HTML
86 lines
3.0 KiB
HTML
<HTML>
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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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</CENTER>
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<HR>
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<H3>fix print command
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</H3>
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<P><B>Syntax:</B>
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</P>
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<PRE>fix ID group-ID print N string keyword value ...
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</PRE>
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<UL><LI>ID, group-ID are documented in <A HREF = "fix.html">fix</A> command
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<LI>print = style name of this fix command
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<LI>N = print every N steps
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<LI>string = text string to print with optional variable names
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<LI>zero or more keyword/value pairs may be appended
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<LI>keyword = <I>file</I> or <I>screen</I>
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<PRE> <I>file</I> value = filename
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<I>screen</I> value = <I>yes</I> or <I>no</I>
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</PRE>
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</UL>
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<P><B>Examples:</B>
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</P>
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<PRE>fix extra all print 100 "Coords of marker atom = $x $y $z"
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fix extra all print 100 "Coords of marker atom = $x $y $z" file coord.txt
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</PRE>
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<P><B>Description:</B>
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</P>
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<P>Print a text string every N steps during a simulation run. This can
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be used for diagnostic purposes or as a debugging tool to monitor some
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quantity during a run. The text string must be a single argument, so
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it should be enclosed in double quotes if it is more than one word.
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If it contains variables it must be enclosed in double quotes to
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insure they are not evaluated when the input script line is read, but
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will instead be evaluated each time the string is printed.
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</P>
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<P>See the <A HREF = "variable.html">variable</A> command for a description of <I>equal</I>
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style variables which are the most useful ones to use with the fix
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print command, since they are evaluated afresh each timestep that the
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fix print line is output. Equal-style variables calculate formulas
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involving mathematical operations, atom properties, group properties,
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thermodynamic properties, global values calculated by a
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<A HREF = "compute.html">compute</A> or <A HREF = "fix.html">fix</A>, or references to other
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<A HREF = "variable.html">variables</A>.
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</P>
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<P>If the <I>file</I> keyword is used, a filename is specified to which the
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output generated by this fix will be written.
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</P>
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<P>If the <I>screen</I> keyword is used, output by this fix to the screen and
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logfile can be turned on or off as desired.
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</P>
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<P><B>Restart, fix_modify, output, run start/stop, minimize info:</B>
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</P>
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<P>No information about this fix is written to <A HREF = "restart.html">binary restart
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files</A>. None of the <A HREF = "fix_modify.html">fix_modify</A> options
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are relevant to this fix. No global scalar or vector or per-atom
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quantities are stored by this fix for access by various <A HREF = "Section_howto.html#4_15">output
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commands</A>. No parameter of this fix can be
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used with the <I>start/stop</I> keywords of the <A HREF = "run.html">run</A> command.
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This fix is not invoked during <A HREF = "minimize.html">energy minimization</A>.
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</P>
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<P><B>Restrictions:</B> none
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</P>
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<P><B>Related commands:</B>
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</P>
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<P><A HREF = "variable.html">variable</A>, <A HREF = "print.html">print</A>
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</P>
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<P><B>Default:</B>
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</P>
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<P>The option defaults are no file output and screen = yes.
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</P>
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</HTML>
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