1. Center for Computational Materials Science, Naval Research Laboratory, Washington, D.C. 20375-5341, United States
2. Department of Chemistry, Mount Saint Vincent University, Halifax, Nova Scotia, Canada B3M2J6
3. Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, Canada, B3H 4J3
4. Hunter College and the Graduate School, City University of New York, New York, New York 10065, United States