1. Department of Chemistry, North Carolina State University, Raleigh, North Carolina
27695-8204, United States
2. Department of Applied Physics, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094, P.
R. China
3. Key Laboratory of
Computational Physical Sciences (Ministry of Education) and Department
of Physics, Fudan University, Shanghai
200433, P. R. China
4. Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
5. Department of Physics, University of Virginia, Charlottesville, Virginia 22904-4714, United
States
6. Institute for Solid State
Physics, University of Tokyo, Kashiwa,
Chiba 277-8581, Japan