Simulation got stuck after this message "Per MPI rank memory allocation (min/avg/max) = 68.21 | 68.21 | 68.21 Mbytes"

I think what Axel means is that there is insufficient information provided to give any meaningful help. Please follow the guidelines for the forum, see: Guidelines for posting questions to the LAMMPS forum and Please Read This First: Guidelines and Suggestions for posting LAMMPS questions.