1. School of Physical Science and Technology, Key Laboratory of Advanced Technologies of Materials, Ministry of Education of China, Southwest Jiaotong University, Chengdu 610031, China
2. Department of Chemistry, University of Puerto Rico, Rio Piedras Campus, San Juan, PR 00931, USA
3. Beijing Computational Science Research Center, Haidian District, Beijing 100193, China
4. Department of Physics and Centre for Advanced Two-Dimensional Materials, National University of Singapore, Singapore 117551, Singapore