1. School of Physics, Central South University, Changsha, Hunan 410083, China
2. School of Chemistry, Southwest Jiaotong University, Chengdu, Sichuan 610031, China
3. The State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China
4. Department of Nanoscience, Joint School of Nanoscience and Nanoengineering, University of North Carolina at Greensboro, Greensboro, NC 27401, USA