On May 26, 2010, at 22:46 , Vikas Varshney wrote: > PARA_PREFIX = ~/local/openmpi/bin/mpiexec -n 4 you mean: PARA_PREFIX = "~/local/openmpi/bin/mpiexec -n 4" ? P. --- Paolo Giannozzi, Dept of Physics, University of Udine via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222