1. State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, People’s Republic of China
2. Beijing Computational Science Research Center, Beijing 100086, People’s Republic of China
3. Department of Chemistry and Biochemistry, California State University Northridge, Northridge, California 91330, USA
4. Materials Research Lab, University of California Santa Barbara, Santa Barbara, California 93110, USA