add compute_pace_atom.rst

doc/src/compute_pace_atom.rst

@@ -0,0 +1,73 @@
+.. index:: compute pace/atom
+
+compute pace/atom command
+=======================
+
+Syntax
+""""""
+
+.. parsed-literal::
+
+   compute ID all pace/atom
+
+* ID is documented in :doc:`compute <compute>` command
+* pace/atom = style name of this compute command
+
+Examples
+""""""""
+
+.. code-block:: LAMMPS
+
+   compute my_gamma all pace/atom
+
+Description
+"""""""""""
+
+Define a computation that calculates both per-atom and per-structure extrapolation grades for PACE interatomic potential.
+Pair style :doc:`pair_style pace/al <pair_pace>` must be instantiated before.
+Extrapolation grades are computed by `pair_style pace/al` every *gamma_freq* steps (see :doc:`pair_style pace/al <pair_pace>`),
+but `compute pace/atom` will invoke extra calculations with this pair style if necessary.
+For better performance, it is recommended to use the same values of *gamma_freq* and
+the frequency of compute style callers, i.e. `dump` or `thermo`.
+
+
+Default compute style with ID="pace_gamma" is always created by `pair_style pace/al` and corresponding
+per-structure and per-atom extrapolation grades could be used as:
+
+.. code-block::
+
+   # per-structure extrapolation grade c_pace_gamma
+   thermo_style custom step etotal temp press c_pace_gamma
+
+   # per-atom extrapolation grade c_pace_gamma
+   dump 1 all custom 100 my.dump id type mass x y z c_pace_gamma
+
+
+Output info
+"""""""""""
+
+This compute calculates both per-atom vector and per-structure scalar,
+which can be accessed by any command that uses per-atom and/or per-structure values from a compute as input.
+See the :doc:`Howto output <Howto_output>` page for an overview of
+LAMMPS output options.
+
+All values are unitless.
+
+Restrictions
+""""""""""""
+
+ Pair style :doc:`pair_style pace/al <pair_pace>` must be instantiated before.
+
+ group-ID always corresponds to the group atoms used by `pair_style pace/al` and by default is `all`.
+
+Related commands
+""""""""""""""""
+
+:doc:`pair_style pace/al <pair_pace>`
+:doc:`dump custom <dump>`
+:doc:`thermo custom <thermo>`
+
+Default
+"""""""
+
+`compute pace_gamma all pace/atom`