1. Key Laboratory of Computational Physical Sciences (Ministry of Education), and Department of Physics, Fudan University, Shanghai 200433, P. R. China
2. State Key Lab of Superhard Materials, Jilin University, Changchun 130012, China
3. Department of Material Science and Engineering, Hefei National Laboratory for Physical Science at the Microscale, and CAS Key Lab of Materials for Energy Conversion, University of Science and Technology of China, Hefei, Anhui, 230026, China
4. National Renewable Energy Laboratory, Golden, Colorado 80401, United States