Hi, I am getting the following error while using the command - [root@localhost INGT]# mpirun -np 24 mdrun_mpi -v -deffnm npt Error - /usr/bin/mpdroot: open failed for root's mpd conf filempiexec_localhost.localdomain (__init__ 1208): forked process failed; status=255 I complied gromacs using - ./configure --enable-shared --enable-mpi. I have installed the mpich package , this is what I get when I check for mpirun and mpiexec - [root@localhost /]# which mpirun /usr/bin/mpirun [root@localhost /]# which mpiexec /usr/bin/mpiexec What could be the problem here ?? Thanks -------- Bharat