forked from lijiext/lammps
70 lines
2.4 KiB
HTML
70 lines
2.4 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 evaporate 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 evaporate N M region-ID seed
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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>evaporate = style name of this fix command
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<LI>N = delete atoms every this many timesteps
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<LI>M = number of atoms to delete each time
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<LI>region-ID = ID of region within which to perform deletions
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<LI>seed = random number seed to use for choosing atoms to delete
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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 solvent evaporate 1000 10 surface 49892
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</PRE>
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<P><B>Description:</B>
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</P>
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<P>Remove M atoms from the simulation every N steps. This can be used,
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for example, to model evaporation of solvent particles (i.e. drying)
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of a system. Every N steps, the number of atoms in the fix group and
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within the specifed region are counted. M of these are chosen at
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random and deleted. If there are less than M eligible particles, then
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all of them are deleted.
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</P>
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<P>Note that you cannot currently delete solvent molecules with this
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command, only individual atoms. If you delete only one atom in a
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molecule, an error will result.
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</P>
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<P>Note that neighbor lists are re-built on timesteps that atoms are
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removed. Thus you should not remove atoms too frequently or you will
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incur overhead due to the cost of building neighbor lists.
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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.
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</P>
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<P>The cummulative number of deleted atoms is stored as a scalar quantity
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by this fix. This quantity can be accessed by various <A HREF = "Section_howto.html#4_15">output
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commands</A>. The scalar value is "intensive",
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meaning it is independent of the number of atoms in the simulation.
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</P>
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<P>No parameter of this fix can be used with the <I>start/stop</I> keywords of
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the <A HREF = "run.html">run</A> command. This fix is not invoked during <A HREF = "minimize.html">energy
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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 = "fix_deposit.html">fix deposit</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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