1. U.S. Naval Academy, Department of Physics, Annapolis, Maryland 21402, USA
2. U.S. Naval Research Laboratory, Center for Computational Materials Science, Washington, DC 20375, USA
3. U.S. Department of Energy, Office of Basic Energy Sciences, Washington, DC 20585, USA
4. Department of Electrical and Computer Engineering, Howard University, 2300 Sixth Street NW, Washington, DC 20059, USA
5. Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA