1. Department of Chemistry and Ames Laboratory, Iowa State University, Ames, Iowa 50011, United States
2. Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
3. Department of Physics, North Carolina A&T State University, Greensboro, North Carolina 27411, United States
4. Department
of Chemistry and Quantum Theory Group, Tulane University, New Orleans, Louisiana 70118, United States