1. Frontier Institute
of Science
and Technology (FIST), Xi’an Jiaotong University, Xi’an 710054, P. R. China
2. Department of Physics, South University of Science and Technology of China, Shenzhen 518055, P.R. China
3. Department
of Physics and Fujian
Provincial Key Laboratory of Theoretical and Computational Chemistry, Xiamen University, Xiamen 361005, P. R. China