For a long time, I’ve had trouble installing nwchem using the directions suggested in the official website. GA tools is usually the culprit. For some reason, the tools included in the nwchem source code don’t work, and one has to import them from somewhere else, or simply try a different development version. This post is very useful: http://www.nwchem-sw.org/index.php/Special:AWCforum/st/id1401/HOWTO%3A_compiling_nwchem-6.5_beta….html