git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@14950 f3b2605a-c512-4ea7-a41b-209d697bcdaa

doc/html/_sources/compute_event_displace.txt

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+.. index:: compute event/displace
+
+compute event/displace command
+==============================
+
+Syntax
+""""""
+
+.. parsed-literal::
+
+   compute ID group-ID event/displace threshold
+
+* ID, group-ID are documented in :doc:`compute <compute>` command
+* event/displace = style name of this compute command
+* threshold = minimum distance anyparticle must move to trigger an event (distance units)
+
+Examples
+""""""""
+
+.. parsed-literal::
+
+   compute 1 all event/displace 0.5
+
+Description
+"""""""""""
+
+Define a computation that flags an "event" if any particle in the
+group has moved a distance greater than the specified threshold
+distance when compared to a previously stored reference state
+(i.e. the previous event).  This compute is typically used in
+conjunction with the :doc:`prd <prd>` and :doc:`tad <tad>` commands, 
+to detect if a transition
+to a new minimum energy basin has occurred.
+
+This value calculated by the compute is equal to 0 if no particle has
+moved far enough, and equal to 1 if one or more particles have moved
+further than the threshold distance.
+
+.. note::
+
+   If the system is undergoing significant center-of-mass motion, 
+   due to thermal motion, an external force, or an initial net momentum, 
+   then this compute will not be able to distinguish that motion from
+   local atom displacements and may generate "false postives."
+
+**Output info:**
+
+This compute calculates a global scalar (the flag).  This value can be
+used by any command that uses a global scalar value from a compute as
+input.  See :ref:`Section_howto 15 <howto_15>` for an
+overview of LAMMPS output options.
+
+The scalar value calculated by this compute is "intensive".  The
+scalar value will be a 0 or 1 as explained above.
+
+Restrictions
+""""""""""""
+
+
+This command can only be used if LAMMPS was built with the REPLICA
+package.  See the :ref:`Making LAMMPS <start_3>` section
+for more info on packages.
+
+Related commands
+""""""""""""""""
+
+:doc:`prd <prd>`, :doc:`tad <tad>`
+
+**Default:** none
+
+
+.. _lws: http://lammps.sandia.gov
+.. _ld: Manual.html
+.. _lc: Section_commands.html#comm