Is KOKKOS GPU acceleration planned for fix qeq/rel/reaxff?

LAMMPS LAMMPS Development
, ,
1

Dear LAMMPS developers,

My planned computing environment is as follows:

  • LAMMPS version: 30 Sep 2026 (stable release)

  • GPU: NVIDIA GPU

  • GPU acceleration: KOKKOS/CUDA

According to the LAMMPS documentation, pair_style reaxff/kk, fix efield/kk, and fix qeq/reaxff/kk are available for GPU acceleration of ReaxFF interactions, external electric field forces, and conventional charge equilibration, respectively.

However, the documentation indicates that the conventional fix qeq/reaxff requires the electric field to be applied along a non-periodic direction when accounting for its effect on charge equilibration. In contrast, fix qeq/rel/reaxff (QEqR) supports electric-field coupling under periodic boundary conditions, making it more suitable for my simulations.

I noticed that, as of the 30 Sep 2026 stable release, fix qeq/rel/reaxff does not appear to have a KOKKOS-accelerated version. Consequently, QEqR calculations may still need to run on the CPU when combined with KOKKOS-accelerated ReaxFF simulations, potentially introducing CPU–GPU data transfers and synchronization overhead that could reduce overall simulation performance.

I would therefore like to ask whether a KOKKOS GPU implementation of fix qeq/rel/reaxff is currently under development or planned for a future LAMMPS release.

Thank you very much for your time and assistance!

2

It wasn’t on our immediate list, but we have been trying in recent months - with the help of AI coding agents - to bring multiple accelerator packages closer to feature parity with the non-accelerated code. So there is a candidate now in ReaxFF: extended-Lagrangian charge equilibration, OPENMP and KOKKOS ports, and consistency fixes by akohlmey · Pull Request #5242 · lammps/lammps · GitHub
This will need careful review and testing from a LAMMPS KOKKOS expert, since we had coding agents in the past produce inferior code for complex problems and thus we had to discard those parts. But there were also many successes… If the changes pass testing, they will be included in the next feature release currently planned for mid November.

4

Thank you very much for your detailed response and for sharing PR #5242.

It is great to see that a KOKKOS implementation of fix qeq/rel/reaxff is already being developed and tested. I will follow the progress of this pull request and look forward to its possible inclusion in the upcoming feature release.

I really appreciate your efforts and those of the LAMMPS development team!