Best use OSC mpiexec to launch mpich2 jobs within torque. http://www.osc.edu/~pw/mpiexec/index.php Note that the pbs_mom conceptually replaces the mpds in the OSC mpiexec+torque+mpich2 case, so you don't mpdboot etc., and you use osc mpiexec instead of the mpiexec(s) built as part of mpich2