Anyway, since I'm using openmpi on my rocks cluster(s), I figure I might as well start using openmpi on debian too. In addition, the only way you can get nwchem 6.0 to work with mpich2 on debian seems to be by using the old v1.2 package which causes problems of its own (see apt-pinning).
Note: See here for information about python support: http://verahill.blogspot.com.au/2012/04/adding-python-support-to-nwchem-under.html
Long story short -- nwchem with openmpi:
sudo apt-get install openmpi-bin libopenmpi-dev
tar -xvf Nwchem-6.0.tar.gz
export LIBMPI="-lmpi -lopen-rte -lopen-pal -ldl -lmpi_f77 -lpthread"
This will take a good 20-30 minutes.
Your binary will be in nwchem-6.0/bin/LINUX64/
Finally, see whether openmpi is already in your LD_LIBRARY_PATH
/lib/openmm:/usr/lib/nvidia-cuda-toolkit:/usr/lib/nvidiaIf not, edit ~/.bashrc and add