Mpirun in lammps

LAMMPS LAMMPS Beginners
1

I’m running lammps parallel using following command
mpirun -np 16 lmp -in in.input
this works fine in my old system, but I recently got a new system and installed lammps with all the pre-requisites. This command outputs same timestep multiple time as if the simulation is running on the specified number of cores together but they are not communicating. (Attaching a screenshot along with).
What should I check in the installation for this?

Screenshot 2022-07-01 151605
Screenshot 2022-07-01 1516051212×967 160 KB

2

This usually happens when either your “mpirun” command belongs to a different MPI package than LAMMPS was compiled with (e.g. MPICH vs. OpenMPI vs. IntelMPI) and you forgot to load the correct environment module or didn’t source the necessary initialization script. Or when LAMMPS was compiled as a serial executable (e.g. when CMake could not detect the MPI development package, but the MPI runtime is installed).

Please check the output of:

  • mpirun --version | head -2
  • lmp -h | grep ^MPI
3

Thanks Alex! BUILD_MPI did the trick.

4

I had the same problem. I recompiled LAMMPS (although with make and not cmake) after installing the right version of Open MPI and it was solved. Thanks!