"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 morse command :h3
pair_style morse/opt command :h3

[Syntax:]

pair_style morse cutoff :pre

cutoff = global cutoff for Morse interactions (distance units) :ul

[Examples:]

pair_style morse 2.5
pair_style morse/opt 2.5
pair_coeff * * 100.0 2.0 1.5
pair_coeff 1 1 100.0 2.0 1.5 3.0 :pre

[Description:]

Style {morse} computes pairwise interactions with the formula

:c,image(Eqs/pair_morse.jpg)

Rc is the cutoff.

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:

D0 (energy units)
alpha (1/distance units)
r0 (distance units)
cutoff (distance units) :ul

The last coefficient is optional.  If not specified, the global morse
cutoff is used.

Style {morse/opt} is an optimized version of style {morse} that should
give identical answers.  Depending on system size and the processor
you are running on, it may be 5-25% faster (for the pairwise portion
of the run time).

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

None of these pair styles support mixing.  Thus, coefficients for all
I,J pairs must be specified explicitly.

All of these pair styles support the "pair_modify"_pair_modify.html
shift option for the energy of the pair interaction.

The "pair_modify"_pair_modify.html table options is not relevant for
the Morse pair styles.

None of these pair styles support the "pair_modify"_pair_modify.html
tail option for adding long-range tail corrections to energy and
pressure.

All of these pair styles write their information to "binary restart
files"_restart.html, so pair_style and pair_coeff commands do not need
to be specified in an input script that reads a restart file.

These pair styles can only be used via the {pair} keyword of the
"run_style respa"_run_style.html command.  They do not support the
{inner}, {middle}, {outer} keywords.

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[Restrictions:]

The {morse/opt} style is part of the "opt" package.  It is only
enabled if LAMMPS was built with that package.  See the "Making
LAMMPS"_Section_start.html#2_3 section for more info.

[Related commands:]

"pair_coeff"_pair_coeff.html

[Default:] none
