1. Chemistry & Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
2. Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
3. T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, California 91125, United States
4. Center for Computational Materials Science, Naval Research Laboratory, Washington, District of Columbia 20375, United States