7.4.5. OPT package
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.
Any hardware. Any compiler.
Building LAMMPS with the OPT package
See the Build extras 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
Use the “-sf opt” command-line switch, 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 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
Speed-up 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.