1. State Key Laboratory
of Superhard Materials, Jilin University, Changchun 130012, People’s Republic of China
2. Department of Physics, Nanyang Normal University, Nanyang 473061, People’s Republic of China
3. Beijing Computational Science Research Center, Beijing 10084, People’s Republic of China
4. Materials Department and Materials Research Laboratory, University of California, Santa Barbara, California 93106-5050, United States