1. State Key Laboratory of Superhard Materials College of Physics Jilin University Changchun 130012 China
2. State Key Laboratory of Inorganic Synthesis and Preparative Chemistry Jilin University Changchun 130012 China
3. Institute of Theoretical Chemistry College of Chemistry Jilin University Changchun 130012 China
4. Department of Chemistry University of Texas at San Antonio San Antonio Texas 78249-0698 USA