/usr/lib/libgmx_mpi.mpich.so is in gromacs-mpich 4.6.5-1build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/libgmx_mpi.mpich.so.8
/usr/lib/libgmx_mpi.mpich.so.8