"Higher level section"_Speed.html - "LAMMPS WWW Site"_lws - "LAMMPS
Documentation"_ld - "LAMMPS Commands"_lc :c

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

:line

OPT package :h3

The OPT package was developed by James Fischer (High Performance
Technologies), David Richie, and Vincent Natoli (Stone Ridge
Technologies).  It contains a handful of pair styles whose compute()
methods were rewritten in C++ templated form to reduce the overhead
due to if tests and other conditional code.

[Required hardware/software:]

None.

[Building LAMMPS with the OPT package:]

See the "Build extras"_Build_extras.html#opt doc page for instructions.

[Run with the OPT package from the command line:]

lmp_mpi -sf opt -in in.script                # run in serial
mpirun -np 4 lmp_mpi -sf opt -in in.script   # run in parallel :pre

Use the "-sf opt" "command-line switch"_Run_options.html, which will
automatically append "opt" to styles that support it.

[Or run with the OPT package by editing an input script:]

Use the "suffix opt"_suffix.html command, or you can explicitly add an
"opt" suffix to individual styles in your input script, e.g.

pair_style lj/cut/opt 2.5 :pre

[Speed-ups to expect:]

You should see a reduction in the "Pair time" value printed at the end
of a run.  On most machines for reasonable problem sizes, it will be a
5 to 20% savings.

[Guidelines for best performance:]

Just try out an OPT pair style to see how it performs.

[Restrictions:]

None.
