1. Hunan Key Laboratory for Micro−Nano Energy Materials and Devices, School of Physics and Optoelectronic, Xiangtan University, Xiangtan 411105, China
2. School of Mathematics and Computational Science, Xiangtan University, Xiangtan 411105, China
3. National Center for Applied Mathematics in Hunan, Xiangtan University, Xiangtan 411105, China