I am using 32 cores on cray system using aprun -n 32 -N 32 ~/Nwchem-6.5/bin/LINUX64/nwchem nwc.res.nw >nwc.freq.out, whreas in the Ubuntu workstation, I am using 6 processors with ~/openmpi/bin/mpirun -np 6 ~/Nwchem-6.5/bin/LINUX64/nwchem nwc.res.nw >nwc.freq.out script for running NWChem. Thanks.