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USER-OPENMP

Install.sh
README
dihedral_harmonic_omp.cpp
dihedral_harmonic_omp.h
dihedral_helix_omp.cpp
dihedral_helix_omp.h
dihedral_multi_harmonic_omp.cpp
dihedral_multi_harmonic_omp.h
dihedral_omp.cpp
dihedral_omp.h
dihedral_opls_omp.cpp
dihedral_opls_omp.h
ewald_omp.cpp
ewald_omp.h
pair_airebo_omp.cpp
pair_airebo_omp.h
pair_born_coul_long_omp.cpp
pair_born_coul_long_omp.h
pair_buck_coul_cut_omp.cpp
pair_buck_coul_cut_omp.h
pair_buck_coul_long_omp.cpp
pair_buck_coul_long_omp.h
pair_buck_omp.cpp
pair_buck_omp.h
pair_cg_cmm_omp.cpp
pair_cg_cmm_omp.h
pair_coul_cut_omp.cpp
pair_coul_cut_omp.h
pair_coul_debye_omp.cpp
pair_coul_debye_omp.h
pair_coul_diel_omp.cpp
pair_coul_diel_omp.h
pair_coul_long_omp.cpp
pair_coul_long_omp.h
pair_dpd_omp.cpp
pair_dpd_omp.h
pair_dpd_tstat_omp.cpp
pair_dpd_tstat_omp.h
pair_eam_alloy_omp.cpp
pair_eam_alloy_omp.h
pair_eam_fs_omp.cpp
pair_eam_fs_omp.h
pair_eam_omp.cpp
pair_eam_omp.h
pair_gauss_cut_omp.cpp
pair_gauss_cut_omp.h
pair_lj96_cut_omp.cpp
pair_lj96_cut_omp.h
pair_lj_charmm_coul_charmm_implicit_omp.cpp
pair_lj_charmm_coul_charmm_implicit_omp.h
pair_lj_charmm_coul_charmm_omp.cpp
pair_lj_charmm_coul_charmm_omp.h
pair_lj_charmm_coul_long_omp.cpp
pair_lj_charmm_coul_long_omp.h
pair_lj_cut_coul_cut_omp.cpp
pair_lj_cut_coul_cut_omp.h
pair_lj_cut_coul_debye_omp.cpp
pair_lj_cut_coul_debye_omp.h
pair_lj_cut_coul_long_omp.cpp
pair_lj_cut_coul_long_omp.h
pair_lj_cut_omp.cpp
pair_lj_cut_omp.h
pair_lj_expand_omp.cpp
pair_lj_expand_omp.h
pair_lj_gromacs_coul_gromacs_omp.cpp
pair_lj_gromacs_coul_gromacs_omp.h
pair_lj_gromacs_omp.cpp
pair_lj_gromacs_omp.h
pair_lj_smooth_omp.cpp
pair_lj_smooth_omp.h
pair_morse_omp.cpp
pair_morse_omp.h
pair_omp.cpp
pair_omp.h
pair_soft_omp.cpp
pair_soft_omp.h
pair_sw_omp.cpp
pair_sw_omp.h
pair_table_omp.cpp
pair_table_omp.h
pair_tersoff_omp.cpp
pair_tersoff_omp.h
pair_tersoff_zbl_omp.cpp
pair_tersoff_zbl_omp.h
pair_yukawa_omp.cpp
pair_yukawa_omp.h

README

The files in this directory are a user-contributed package for LAMMPS.

The person who created these files is Axel Kohlmeyer (axel.kohlmeyer@temple.edu) with the help of Ryan Houlihan and Peter Shannon. Contact Axel directly if you have questions or for example scripts that use it.

This package implements a number of pair styles that support multi-level parallelism using OpenMP in combination with message passing via MPI in LAMMPS.

In general, the message passing version of LAMMPS parallelizes very well, but in certain scenarios, hybrid threading plus message passing parallelization can provide an extra speedup. For example:

  • LAMMPS is in parallel over a TCP/IP network with high latencies that limit scaling.
  • LAMMPS is run across many-core nodes where node-to-node bandwidth is limited
  • The input is using a functionality that has unfavorable scaling yet needs to be run across a large number of processors for acceptable throughput, e.g. the PPPM kspace style.

In many cases a speedup of 2x or better over the best MPI-only effort has been observed. The benefit is usually the largest when the parallel efficiency of the MPI parallelization is dropping, i.e. there are only a few thousand atoms or less per MPI task.

Also, most of the pair styles contain little optimizations that make the /omp variants faster than the corresponding regular pair styles, even when LAMMPS was compiled without OpenMP support, or only one thread per MPI task is used.

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