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

doc/html/_sources/fix_store_force.txt

@@ -0,0 +1,80 @@
+.. index:: fix store/force
+
+fix store/force command
+=======================
+
+Syntax
+""""""
+
+.. parsed-literal::
+
+   fix ID group-ID store/force
+
+* ID, group-ID are documented in :doc:`fix <fix>` command
+* store/force = style name of this fix command
+
+Examples
+""""""""
+
+.. parsed-literal::
+
+   fix 1 all store/force
+
+Description
+"""""""""""
+
+Store the forces on atoms in the group at the point during each
+timestep when the fix is invoked, as described below.  This is useful
+for storing forces before constraints or other boundary conditions are
+computed which modify the forces, so that unmodified forces can be
+:doc:`written to a dump file <dump>` or accessed by other :ref:`output commands <howto_15>` that use per-atom quantities.
+
+This fix is invoked at the point in the velocity-Verlet timestepping
+immediately after :doc:`pair <pair_style>`, :doc:`bond <bond_style>`,
+:doc:`angle <angle_style>`, :doc:`dihedral <dihedral_style>`,
+:doc:`improper <improper_style>`, and :doc:`long-range <kspace_style>`
+forces have been calculated.  It is the point in the timestep when
+various fixes that compute constraint forces are calculated and
+potentially modify the force on each atom.  Examples of such fixes are
+:doc:`fix shake <fix_shake>`, :doc:`fix wall <fix_wall>`, and :doc:`fix indent <fix_indent>`.
+
+.. note::
+
+   The order in which various fixes are applied which operate at
+   the same point during the timestep, is the same as the order they are
+   specified in the input script.  Thus normally, if you want to store
+   per-atom forces due to force field interactions, before constraints
+   are applied, you should list this fix first within that set of fixes,
+   i.e. before other fixes that apply constraints.  However, if you wish
+   to include certain constraints (e.g. fix shake) in the stored force,
+   then it could be specified after some fixes and before others.
+
+Restart, fix_modify, output, run start/stop, minimize info
+""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+No information about this fix is written to :doc:`binary restart files <restart>`.  None of the :doc:`fix_modify <fix_modify>` options
+are relevant to this fix.
+
+This fix produces a per-atom array which can be accessed by various
+:ref:`output commands <howto_15>`.  The number of columns
+for each atom is 3, and the columns store the x,y,z forces on each
+atom.  The per-atom values be accessed on any timestep.
+
+No parameter of this fix can be used with the *start/stop* keywords of
+the :doc:`run <run>` command.  This fix is not invoked during :doc:`energy minimization <minimize>`.
+
+Restrictions
+""""""""""""
+ none
+
+Related commands
+""""""""""""""""
+
+:doc:`fix store_state <fix_store_state>`
+
+**Default:** none
+
+
+.. _lws: http://lammps.sandia.gov
+.. _ld: Manual.html
+.. _lc: Section_commands.html#comm