Lammps operational issues:A multi-core operation suddenly becomes a single-core operation multiple times

Hello everyone:
My lammps had the following problem: my computer was using the Windows version of lammps, and I didn’t have any problems running before, but then one day when I was running multi-core, such as a quad-core run, lammps showed up as a single-core operation and run four times, so I wanted to know how to solve this problem.
At the same time, I uninstalled and reinstalled lammps and mpich, and it still didn’t solve the problem

This will happen when either:

  • the mpiexec command is not from the same MPI library that was used to compile LAMMPS, or
  • the LAMMPS executable was not compiled for MPI parallelism

Only you can know which of the two cases applies. You can tell the latter is true when running lmp -h and you will get a line like this:

MPI v1.0: LAMMPS MPI STUBS for LAMMPS version 28 Mar 2023

Yes agreed, I’ve seen this multiple times.