I know that might files are usually used on when running simulations in parallel. However, I was wondering if we’d need it for depletion simulations not in parallel. Thank you.
mpi4py is only required if you wish to run openmc + depletion in parallel with distributed memory under mpi. In this case, each computational node is responsible for depleting a subset of materials and reporting back to the main data file.
If you run openmc + depletion without mpi, then you don’t need mpi4py. Materials are still depleted “in parallel” via the python multiprocessing module. This is also the case when running under mpi.
If you want to run entirely in serial (no mpi, no multiprocessing), set openmc.deplete.pool.USE_MULTIPROCESSING = False - openmc.deplete – Depletion — OpenMC Documentation