1. Institute
of Theoretical Chemistry, Jilin University, Changchun, Jilin 130021, P. R. China
2. College
of Physics and Laboratory of Fiber Materials and Modern Textile, Growing
Base for State Key Laboratory, Qingdao University, Qingdao, Shandong 266071, P. R. China
3. Ames
Laboratory—U.S. DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, United States