LAMMPS run problem

Dear LAMMPS developers,

I wanted to use MPI to run my script and used this command “mpiexec -np 4 lmp -in tt.lmp” but the run shows that my computer is only using one processor.
How can I fix this problem?


This means that either your LAMMPS version does not support parallel computing with MPI or that you used an mpiexec program that belongs to a different MPI library than the one that was used to compile LAMMPS. In order to tell which is the case, more information is needed.

  • the output of lmp -h up to where is says List of individual style options included in this LAMMPS executable
  • if you are running on Linux or macOS: the output of which mpiexec and the output of which mpirun

Sorry for the late reply. The relevant document is attached below。

log.lammps (356.9 KB)

This is NOT what I had asked for.

I’m sorry I didn’t understand correctly. Is this what you ask for?
Output.txt (3.0 KB)


The relevant information is this bit:

OS: Windows 10 22H2, Windows ABI 6.2 (9200) on x86_64

Compiler: MinGW-w64 64bit 9.0 / GNU C++ 11.2.1 20210728 (Fedora MinGW 11.2.1-3.fc35) with OpenMP 4.5
C++ standard: C++14
MPI v1.0: LAMMPS MPI STUBS for LAMMPS version 22 Dec 2022

This says that you are running on Windows 10 and that you installed a LAMMPS executable from the installer repository without MPI support. LAMMPS cannot be compiled without an MPI library present, but LAMMPS MPI STUBS means that LAMMPS uses an internal MPI library that “fakes” what an MPI library does for just a single process.
You need to uninstall that version of LAMMPS and a version that has been compiled with the MPI library that you are using to have a version that can run in parallel with MPI. Otherwise you are limited to multi-threading with either the KOKKOS, INTEL, or OPENMP package.

Thanks so much!