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>fix gyration 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 gyration N file
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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>gyration = style name of this fix command
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<LI>N = compute radius-of-gyration every this many timesteps
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<LI>file = filename to write gyration info to
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</UL>
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<P><B>Examples:</B>
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</P>
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<PRE>fix 1 all gyration 100 molecule.out
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</PRE>
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<P><B>Description:</B>
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</P>
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<P>Compute the radius-of-gyration of the group of atoms every N steps,
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including all effects due to atoms passing thru periodic boundaries.
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Write the results to the specified file.
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</P>
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<P>Rg is a measure of the size of the group of atoms, and is computed by
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this formula
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</P>
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<CENTER><IMG SRC = "Eqs/fix_gyration.jpg">
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</CENTER>
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<P>where M is the total mass of the group and Rcm is the center-of-mass
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position of the group.
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</P>
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2007-10-11 06:28:11 +08:00
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<P><B>Restart, fix_modify, output, run start/stop, minimize info:</B>
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2007-06-26 08:03:39 +08:00
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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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2007-10-11 06:28:11 +08:00
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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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2007-06-26 08:03:39 +08:00
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</P>
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2006-09-22 00:22:34 +08:00
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<P><B>Restrictions:</B> none
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</P>
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<P><B>Related commands:</B> none
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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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