1. The Quantum Theory Project, Department of Chemistry, The University of Florida, Gainesville, Florida 32611, USA
2. Washington State University, Pullman, Washington 99164-4630, USA and University of Alabama, Tuscaloosa, Alabama 35487-0336, USA
3. Center for Astrophysics, Harvard|Smithsonian, Cambridge, Massachusetts 02138, USA
4. Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA