1. State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P. R. China
2. School of Physics, Shandong University, Jinan 250100, P. R. China
3. School of Energy and Power Engineering, Shandong University, Jinan 250061, P. R. China
4. Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
5. State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter (FJIRSM), Chinese Academy of Sciences (CAS), Fuzhou 350002, China