Hi All,

I am trying to use hybrid MPI+OpenMP parallelization for DFT on Q-CHEM 4.4. My problem is that when I try to use multiple nodes, I find that QCHEM only uses one of the nodes. We use the pbs scheduler, so in my job submission script I write:
#PBS -l select=2:ncpus=24:mpiprocs=1
which should request 2 nodes, each with 1 mpiproc and 24 cpus.

I use the following line to run QCHEM:
qchem -pbs -np 2 -nt 24 input OUT
The -pbs flag sets MACHINEFILE=${PBS_NODEFILE} and if I understand the manual correctly this should request 2 MPI processes, each with 24 threads.

Am I missing a flag? What am I doing wrong?