1. Department of Chemistry and Physics, Mount Saint Vincent University, Halifax, NS, Canada B3M 2J6
2. Department of Chemistry, Dalhousie University, Halifax, NS, Canada, B3H 4J3
3. Center for Computational Materials Science, Naval Research Laboratory, Washington, D.C. 20375-5341, United States
4. Hunter College and the Graduate School, City University of New York, New York, New York 10065, United States