"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c


:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Section_commands.html#comm)

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pair_style born/coul/long command :h3

[Syntax:]

pair_style born/coul/long cutoff (cutoff2) :pre

cutoff = global cutoff for LJ (and Coulombic if only 1 arg) (distance units)
cutoff2 = global cutoff for Coulombic (optional) (distance units) :ul

[Examples:]

pair_style born/coul/long 10.0
pair_style born/coul/long 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 :pre

[Description:]

This pair style compute the Born-Mayer-Huggins potential described in
"(Fumi and Tosi)"_#FumiTosi, given by

:c,image(Eqs/pair_born.jpg)

where sigma is an interaction-dependent length parameter, rho is an
ionic-pair dependent length parameter, and the last term represents
the usual Coulombic pairwise interaction between atoms I and J.  In
the Coulombic term, k is an energy-conversion constant, Qi and Qj are
the charges on the 2 atoms, and epsilon is the dielectric constant
which can be set by the "dielectric"_dielectric.html command.

If one cutoff is specified in the pair_style command, 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.

Note that this potential is identical to the "Buckingham
potential"_pair_buck.html when sigma = D = 0.

An additional damping factor is applied to the Coulombic term so it
can be used in conjunction with the "kspace_style"_kspace_style.html
command and its {ewald} or {pppm} 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.

The following coefficients must be defined for each pair of atoms
types via the "pair_coeff"_pair_coeff.html command as in the examples
above, or in the data file or restart files read by the
"read_data"_read_data.html or "read_restart"_read_restart.html
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) :ul

The last coefficient is optional.  If not specified, the global A,C,D
cutoff specified in the pair_style command is used.  Only the A,C,D
cutoff can be specified since a Coulombic cutoff cannot be specified
for an individual I,J type pair.  All type pairs use the same global
Coulombic cutoff specified in the pair_style command.

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[Mixing, shift, table, tail correction, restart, rRESPA info]:

This style does not support mixing.  Thus, coefficients for all
I,J pairs must be specified explicitly.

This style supports the "pair_modify"_pair_modify.html shift option
for the energy of the exp(), 1/r^6, and 1/r^8 portion of the pair
interaction.

This style does not support the "pair_modify"_pair_modify.html
table option since a tabulation capability has not yet been added to
this potential.

This style does not support the pair_modify tail option for
adding long-range tail corrections to energy and pressure.

This style writes its information to binary
"restart"_restart.html files, so pair_style and pair_coeff commands do
not need to be specified in an input script that reads a restart file.

This style only supports the {pair} keyword of run_style respa.
See the "run_style"_run_style.html command for details.

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[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 "Making LAMMPS"_Section_start.html#2_3 section for
more info.

[Related commands:]

"pair_coeff"_pair_coeff.html, "pair_style buck"_pair_buck.html

[Default:] none

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:link(FumiTosi)
Fumi and Tosi, J Phys Chem Solids, 25, 31 (1964),
Fumi and Tosi, J Phys Chem Solids, 25, 45 (1964).
