Michael,
1) Did you check from the ompi_info output that OpenMPI was correctly built for multi-threading?
"ompi_info | grep Thread" should show "Thread support: posix (mpi: yes, progress: no)"
2) Let's check if GA/ARMCI built correctly. Could you please post the following
a) $NWCHEM_TOP/src/tools/build/config.log
b) $NWCHEM_TOP/src/tools/build/armci/config.log