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

doc/html/_sources/compute_displace_atom.txt

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+.. index:: compute displace/atom
+
+compute displace/atom command
+=============================
+
+Syntax
+""""""
+
+.. parsed-literal::
+
+   compute ID group-ID displace/atom
+
+* ID, group-ID are documented in :doc:`compute <compute>` command
+* displace/atom = style name of this compute command
+
+Examples
+""""""""
+
+.. parsed-literal::
+
+   compute 1 all displace/atom
+
+Description
+"""""""""""
+
+Define a computation that calculates the current displacement of each
+atom in the group from its original coordinates, including all effects
+due to atoms passing thru periodic boundaries.
+
+A vector of four quantites per atom is calculated by this compute.
+The first 3 elements of the vector are the dx,dy,dz displacements.
+The 4th component is the total displacement, i.e. sqrt(dx*dx + dy*dy +
+dz*dz).
+
+The displacement of an atom is from its original position at the time
+the compute command was issued.  The value of the displacement will be
+0.0 for atoms not in the specified compute group.
+
+.. note::
+
+   Initial coordinates are stored in "unwrapped" form, by using the
+   image flags associated with each atom.  See the :doc:`dump custom <dump>` command for a discussion of "unwrapped" coordinates.
+   See the Atoms section of the :doc:`read_data <read_data>` command for a
+   discussion of image flags and how they are set for each atom.  You can
+   reset the image flags (e.g. to 0) before invoking this compute by
+   using the :doc:`set image <set>` command.
+
+.. note::
+
+   If you want the quantities calculated by this compute to be
+   continuous when running from a :doc:`restart file <read_restart>`, then
+   you should use the same ID for this compute, as in the original run.
+   This is so that the fix this compute creates to store per-atom
+   quantities will also have the same ID, and thus be initialized
+   correctly with time=0 atom coordinates from the restart file.
+
+**Output info:**
+
+This compute calculates a per-atom array with 4 columns, which can be
+accessed by indices 1-4 by any command that uses per-atom values from
+a compute as input.  See :ref:`Section_howto 15 <howto_15>` for an overview of LAMMPS output
+options.
+
+The per-atom array values will be in distance :doc:`units <units>`.
+
+Restrictions
+""""""""""""
+ none
+
+Related commands
+""""""""""""""""
+
+:doc:`compute msd <compute_msd>`, :doc:`dump custom <dump>`, :doc:`fix store/state <fix_store_state>`
+
+**Default:** none
+
+
+.. _lws: http://lammps.sandia.gov
+.. _ld: Manual.html
+.. _lc: Section_commands.html#comm