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Running a MPICH program through mpiexec


Hi! If this is the wrong board to post this question, I'll happily move it!

I'm trying to run a prebuilt LAMMPS Windows executable on my Windows machine. According to their documentation (, they're built for MPICH.

When I try to run it using the mpiexec executable that comes with Parallel studio XE, it works perfectly, but it doesn't spread processors correctly. For example, if I launch it using the option -n 4, instead of running a single LAMMPS executable (lmp_mpi) on 4 cores, it runs the same executable 4 times, allocating one core per executable.

Here's my calling method : mpiexec -localonly -n 4 -genv OMP_NUM_THREADS 1 lmp_mpi -in

I've tried playing with the value of OMP_NUM_THREADS (as my LAMMPS executable should be using OpenMP), but it hasn't given the desired results. What should I do?

Thank you very much! :)


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I found the lines below in the LAMMPS documentation:

Please note, that you need to download a very specific (and somewhat older) version of the MPICH package, as this is what LAMMPS was compiled with and the latest available Windows binary version compatible with the GNU compilers used to compile LAMMPS

They may not support the latest versions of MPICH and Intel MPI. Please ask LAMMPS developers about it.


Best regards, Anatoliy

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