2009-10-30 06:41:53 +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>compute event/displace command
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</H3>
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<P><B>Syntax:</B>
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</P>
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<PRE>compute ID group-ID event/displace threshold
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</PRE>
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<UL><LI>ID, group-ID are documented in <A HREF = "compute.html">compute</A> command
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<LI>event/displace = style name of this compute command
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2009-10-31 02:13:57 +08:00
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<LI>threshold = minimum distance anyparticle must move to trigger an event (distance units)
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2009-10-30 06:41:53 +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>compute 1 all event/displace 0.5
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</PRE>
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<P><B>Description:</B>
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</P>
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2009-10-31 02:13:57 +08:00
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<P>Define a computation that flags an "event" if any particle in the
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group has moved a distance greater than the specified threshold
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distance when compared to a previously stored reference state
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(i.e. the previous event). This compute is typically used in
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2011-01-05 07:39:13 +08:00
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conjunction with the <A HREF = "prd.html">prd</A> and <A HREF = "tad.html">tad</A> commands,
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to detect if a transition
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2009-10-31 02:13:57 +08:00
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to a new minimum energy basin has occurred.
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2009-10-30 06:41:53 +08:00
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</P>
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2009-10-31 02:13:57 +08:00
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<P>This value calculated by the compute is equal to 0 if no particle has
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moved far enough, and equal to 1 if one or more particles have moved
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further than the threshold distance.
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2009-10-30 06:41:53 +08:00
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</P>
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2011-01-05 07:39:13 +08:00
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<P>NOTE: If the system is undergoing significant center-of-mass motion,
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due to thermal motion, an external force, or an initial net momentum,
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then this compute will not be able to distinguish that motion from
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local atom displacements and may generate "false postives."
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2011-07-15 03:37:37 +08:00
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</P>
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<P><B>Output info:</B>
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2009-10-30 06:41:53 +08:00
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</P>
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2009-12-04 07:58:11 +08:00
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<P>This compute calculates a global scalar (the flag). This value can be
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used by any command that uses a global scalar value from a compute as
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2011-12-14 04:43:36 +08:00
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input. See <A HREF = "Section_howto.html#howto_15">Section_howto 15</A> for an
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overview of LAMMPS output options.
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2009-12-04 07:58:11 +08:00
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</P>
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2010-03-03 05:51:16 +08:00
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<P>The scalar value calculated by this compute is "intensive". The
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scalar value will be a 0 or 1 as explained above.
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2010-01-24 07:20:05 +08:00
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</P>
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2009-11-03 01:41:54 +08:00
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<P><B>Restrictions:</B>
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</P>
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2011-08-27 02:53:00 +08:00
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<P>This command can only be used if LAMMPS was built with the REPLICA
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2011-08-26 00:46:23 +08:00
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package. See the <A HREF = "Section_start.html#start_3">Making LAMMPS</A> section
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for more info on packages.
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2009-10-30 06:41:53 +08:00
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</P>
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<P><B>Related commands:</B>
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</P>
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2011-01-05 07:39:13 +08:00
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<P><A HREF = "prd.html">prd</A>, <A HREF = "tad.html">tad</A>
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2009-10-30 06:41:53 +08:00
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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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