GPU package updates Dec 2023

[ndtrung81]

Summary

This PR contains updates and maintenance to the GPU package: adding the GPU version of several pair styles: lj/cut/coul/long/soft, lj/cut/coulcut/soft, coul/long/slater, edpd, mdpd, sph/lj, sph/taitwater, sph/heatconduction; updating the corresponding doc pages, and cleaning up unused variables.

Related Issue(s)

coul/long/slater is added per Feature Request and thus closes #3918

Author(s)

Trung Nguyen (U Chicago)

Licensing

By submitting this pull request, I agree, that my contribution will be included in LAMMPS and redistributed under either the GNU General Public License version 2 (GPL v2) or the GNU Lesser General Public License version 2.1 (LGPL v2.1).

Backward Compatibility

Should maintain backward compatibility

Implementation Notes

1. The pair styles from DPD-MESO and SPH packages demonstrate how to use the extra arrays to store extra_field per-atom data in the GPU package, and how to accumulate/tally per-atom values within the kernels. This is an option to refactor existing Base* classes and to support other AtomVec* classes with extra per-atom data.

2. The pair styles mdpd_rhosum and sph_heatconduction do not calculate atom forces, energy and virial, but rather tallying per-atom values, which are reminiscent of computing density rho in pair eam, and so can be lumped into the actual pair styles.

Post Submission Checklist

• The feature or features in this pull request is complete
• Licensing information is complete
• Corresponding author information is complete
• The source code follows the LAMMPS formatting guidelines
• Suitable new documentation files and/or updates to the existing docs are included
• The added/updated documentation is integrated and tested with the documentation build system
• The feature has been verified to work with the conventional build system
• The feature has been verified to work with the CMake based build system
• Suitable tests have been added to the unittest tree.
• A package specific README file has been included or updated
• One or more example input decks are included

Further Information, Files, and Links

[stanmoore1]

Need to update Commands list, https://github.com/lammps/lammps/blob/develop/doc/src/Commands_pair.rst. Otherwise looks fine to me.

[ndtrung81]

@stanmoore1 thanks, I updated Command_pair.rst and fixed some last-minute issues.