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