1. State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter (FJIRSM) Chinese Academy of Sciences (CAS), Fuzhou 350002, P. R. China
2. University of Chinese Academy of Sciences, Beijing 100049, P. R. China
3. Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou 350108, P. R. China
4. School of Physical Science and Technology & Lanzhou Center for Theoretical Physics, Lanzhou University, Lanzhou 730000, P. R. China
5. Key Laboratory of Optoelectronic Materials Chemistry and Physics, FJIRSM, CAS, Fuzhou 350002, P. R. China
6. North Carolina State University, Raleigh 27695-8204, USA