add born/gauss pair style (for modeling liquid mercury)

doc/src/Commands_pair.rst

@@ -55,6 +55,7 @@ OPT.
    * :doc:`born/coul/msm (o) <pair_born>`
    * :doc:`born/coul/wolf (go) <pair_born>`
    * :doc:`born/coul/wolf/cs (g) <pair_cs>`
+   * :doc:`born/gauss <pair_born_gauss>`
    * :doc:`bpm/spring <pair_bpm_spring>`
    * :doc:`brownian (o) <pair_brownian>`
    * :doc:`brownian/poly (o) <pair_brownian>`

doc/src/pair_born_gauss.rst

@@ -0,0 +1,101 @@
+.. index:: pair_style born/gauss
+
+pair_style born/gauss command
+=============================
+
+Syntax
+""""""
+
+.. code-block:: LAMMPS
+
+   pair_style born/gauss cutoff
+
+* born/gauss = name of the pair style
+* cutoff = global cutoff (distance units)
+
+Examples
+""""""""
+
+.. code-block:: LAMMPS
+
+   pair_style born/gauss 10.0
+   pair_coeff 1 1 1 1 8.2464e13 12.48 0.042644277 0.44 3.56
+
+Description
+"""""""""""
+
+Pair style *born/gauss* computes pairwise interactions from a combination of a Born-Mayer
+repulsive term and a Gaussian attractive term according to :ref:`(Bomont) <Bomont>`:
+
+.. math::
+
+   E = A_0 \exp \left( -\alpha r \right) - A_1 \exp\left[ -\beta \left(r - r_0 \right)^2 \right]
+       \qquad r < r_c
+
+:math:`r_c` is the cutoff.
+
+The following coefficients must be defined for each pair of atoms
+types via the :doc:`pair_coeff <pair_coeff>` command as in the examples
+above, or in the data file or restart files read by the
+:doc:`read_data <read_data>` or :doc:`read_restart <read_restart>`
+commands:
+
+* :math:`A_0` (energy units)
+* :math:`\alpha` (1/distance units)
+* :math:`A_1` (energy units)
+* :math:`\beta` (1/(distance units)^2)
+* :math:`r_0` (distance units)
+* cutoff (distance units)
+
+The last coefficient is optional.  If not specified, the global cutoff is used.
+
+----------
+
+Mixing, shift, table, tail correction, restart, rRESPA info
+"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+This pair style does not support mixing.  Thus, coefficients for all I,J
+pairs must be specified explicitly.
+
+This pair style supports the :doc:`pair_modify <pair_modify>` shift
+option for the energy of the pair interaction.
+
+The :doc:`pair_modify <pair_modify>` table options are not relevant for
+this pair style.
+
+This pair style does not support the :doc:`pair_modify <pair_modify>`
+tail option for adding long-range tail corrections to energy and
+pressure.
+
+This pair style writes its information to :doc:`binary restart files
+<restart>`, so pair_style and pair_coeff commands do not need to be
+specified in an input script that reads a restart file.
+
+This pair style can only be used via the *pair* keyword of the
+:doc:`run_style respa <run_style>` command.  It does not support the
+*inner*, *middle*, *outer* keywords.
+
+----------
+
+Restrictions
+""""""""""""
+
+This pair style is only enabled if LAMMPS was built with the EXTRA-PAIR
+package.  See the :doc:`Build package <Build_package>` page for more
+info.
+
+Related commands
+""""""""""""""""
+
+:doc:`pair_coeff <pair_coeff>`, :doc:`pair_style born <pair_born>`
+
+Default
+"""""""
+
+none
+
+--------------
+
+.. _Bomont:
+
+**(Bomont)** Bomont, Bretonnet, J. Chem. Phys. 124, 054504 (2006)

doc/src/pair_style.rst

@@ -132,6 +132,7 @@ accelerated styles exist.
 * :doc:`born/coul/msm <pair_born>` - Born with long-range MSM Coulomb
 * :doc:`born/coul/wolf <pair_born>` - Born with Wolf potential for Coulomb
 * :doc:`born/coul/wolf/cs <pair_cs>` - Born with Wolf potential for Coulomb and core/shell model
+* :doc:`born/gauss <pair_born_gauss>` - Born-Mayer / Gaussian potential
 * :doc:`bpm/spring <pair_bpm_spring>` - repulsive harmonic force with damping
 * :doc:`brownian <pair_brownian>` - Brownian potential for Fast Lubrication Dynamics
 * :doc:`brownian/poly <pair_brownian>` - Brownian potential for Fast Lubrication Dynamics with polydispersity