Homec4science
Diffusion lammps (lammps-icms) Browse

lammps/doc/html/_sources/pair_born.txt
66312fac551dlammps-icms

Last Change
Raw File

pair_born.txt
View Options

.. index:: pair_style born
pair_style born command
=======================
pair_style born/omp command
===========================
pair_style born/gpu command
===========================
pair_style born/coul/long command
=================================
pair_style born/coul/long/cs command
====================================
pair_style born/coul/long/gpu command
=====================================
pair_style born/coul/long/omp command
=====================================
pair_style born/coul/msm command
================================
pair_style born/coul/msm/omp command
====================================
pair_style born/coul/wolf command
=================================
pair_style born/coul/wolf/gpu command
=====================================
pair_style born/coul/wolf/omp command
=====================================
Syntax
""""""
.. parsed-literal::
pair_style style args
* style = *born* or *born/coul/long* or *born/coul/long/cs* or *born/coul/msm* or *born/coul/wolf*
* args = list of arguments for a particular style
.. parsed-literal::
*born* args = cutoff
cutoff = global cutoff for non-Coulombic interactions (distance units)
*born/coul/long* or *born/coul/long/cs* args = cutoff (cutoff2)
cutoff = global cutoff for non-Coulombic (and Coulombic if only 1 arg) (distance units)
cutoff2 = global cutoff for Coulombic (optional) (distance units)
*born/coul/msm* args = cutoff (cutoff2)
cutoff = global cutoff for non-Coulombic (and Coulombic if only 1 arg) (distance units)
cutoff2 = global cutoff for Coulombic (optional) (distance units)
*born/coul/wolf* args = alpha cutoff (cutoff2)
alpha = damping parameter (inverse distance units)
cutoff = global cutoff for non-Coulombic (and Coulombic if only 1 arg) (distance units)
cutoff2 = global cutoff for Coulombic (optional) (distance units)
Examples
""""""""
.. parsed-literal::
pair_style born 10.0
pair_coeff * * 6.08 0.317 2.340 24.18 11.51
pair_coeff 1 1 6.08 0.317 2.340 24.18 11.51
.. parsed-literal::
pair_style born/coul/long 10.0
pair_style born/coul/long/cs 10.0
pair_style born/coul/long 10.0 8.0
pair_style born/coul/long/cs 10.0 8.0
pair_coeff * * 6.08 0.317 2.340 24.18 11.51
pair_coeff 1 1 6.08 0.317 2.340 24.18 11.51
.. parsed-literal::
pair_style born/coul/msm 10.0
pair_style born/coul/msm 10.0 8.0
pair_coeff * * 6.08 0.317 2.340 24.18 11.51
pair_coeff 1 1 6.08 0.317 2.340 24.18 11.51
.. parsed-literal::
pair_style born/coul/wolf 0.25 10.0
pair_style born/coul/wolf 0.25 10.0 9.0
pair_coeff * * 6.08 0.317 2.340 24.18 11.51
pair_coeff 1 1 6.08 0.317 2.340 24.18 11.51
Description
"""""""""""
The *born* style computes the Born-Mayer-Huggins or Tosi/Fumi
potential described in :ref:`(Fumi and Tosi) <FumiTosi>`, given by
.. image:: Eqs/pair_born.jpg
:align: center
where sigma is an interaction-dependent length parameter, rho is an
ionic-pair dependent length parameter, and Rc is the cutoff.
The styles with *coul/long* or *coul/msm* add a Coulombic term as
described for the :doc:`lj/cut <pair_lj>` pair styles. An additional
damping factor is applied to the Coulombic term so it can be used in
conjunction with the :doc:`kspace_style <kspace_style>` command and its
*ewald* or *pppm* of *msm* option. The Coulombic cutoff specified for
this style means that pairwise interactions within this distance are
computed directly; interactions outside that distance are computed in
reciprocal space.
If one cutoff is specified for the *born/coul/long* and
*born/coul/msm* style, it is used for both the A,C,D and Coulombic
terms. If two cutoffs are specified, the first is used as the cutoff
for the A,C,D terms, and the second is the cutoff for the Coulombic
term.
The *born/coul/wolf* style adds a Coulombic term as described for the
Wolf potential in the :doc:`coul/wolf <pair_coul>` pair style.
Style *born/coul/long/cs* is identical to *born/coul/long* except that
a term is added for the :ref:`core/shell model <howto_25>`
to allow charges on core and shell particles to be separated by r =
0.0.
Note that these potentials are related to the :doc:`Buckingham potential <pair_buck>`.
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, or by mixing as described below:
* A (energy units)
* rho (distance units)
* sigma (distance units)
* C (energy units * distance units^6)
* D (energy units * distance units^8)
* cutoff (distance units)
The second coefficient, rho, must be greater than zero.
The last coefficient is optional. If not specified, the global A,C,D
cutoff specified in the pair_style command is used.
For *born/coul/long* and *born/coul/wolf* no Coulombic cutoff can be
specified for an individual I,J type pair. All type pairs use the
same global Coulombic cutoff specified in the pair_style command.
----------
Styles with a *gpu*\ , *intel*\ , *kk*\ , *omp*\ , or *opt* suffix are
functionally the same as the corresponding style without the suffix.
They have been optimized to run faster, depending on your available
hardware, as discussed in :doc:`Section_accelerate <Section_accelerate>`
of the manual. The accelerated styles take the same arguments and
should produce the same results, except for round-off and precision
issues.
These accelerated styles are part of the GPU, USER-INTEL, KOKKOS,
USER-OMP and OPT packages, respectively. They are only enabled if
LAMMPS was built with those packages. See the :ref:`Making LAMMPS <start_3>` section for more info.
You can specify the accelerated styles explicitly in your input script
by including their suffix, or you can use the :ref:`-suffix command-line switch <start_7>` when you invoke LAMMPS, or you can
use the :doc:`suffix <suffix>` command in your input script.
See :doc:`Section_accelerate <Section_accelerate>` of the manual for
more instructions on how to use the accelerated styles effectively.
----------
**Mixing, shift, table, tail correction, restart, rRESPA info**\ :
These pair styles do not support mixing. Thus, coefficients for all
I,J pairs must be specified explicitly.
These styles support the :doc:`pair_modify <pair_modify>` shift option
for the energy of the exp(), 1/r^6, and 1/r^8 portion of the pair
interaction.
The *born/coul/long* pair style supports the
:doc:`pair_modify <pair_modify>` table option ti tabulate the
short-range portion of the long-range Coulombic interaction.
These styles support the pair_modify tail option for adding long-range
tail corrections to energy and pressure.
Thess styles writes thei information to binary :doc:`restart <restart>`
files, so pair_style and pair_coeff commands do not need to be
specified in an input script that reads a restart file.
These styles can only be used via the *pair* keyword of the :doc:`run_style respa <run_style>` command. They do not support the *inner*\ ,
*middle*\ , *outer* keywords.
----------
Restrictions
""""""""""""
The *born/coul/long* style is part of the KSPACE package. It is only
enabled if LAMMPS was built with that package (which it is by
default). See the :ref:`Making LAMMPS <start_3>` section
for more info.
Related commands
""""""""""""""""
:doc:`pair_coeff <pair_coeff>`, :doc:`pair_style buck <pair_buck>`
**Default:** none
----------
.. _FumiTosi:
Fumi and Tosi, J Phys Chem Solids, 25, 31 (1964),
Fumi and Tosi, J Phys Chem Solids, 25, 45 (1964).
.. _lws: http://lammps.sandia.gov
.. _ld: Manual.html
.. _lc: Section_commands.html#comm
c4science · Help