1. Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), P.O. Box 919-311, Mianyang, Sichuan 621900, P. R. China
2. Beijing Computational Science Research Center, Beijing 100048, P. R. China
3. Department of Applied Chemistry, China Agricultural University, Yuanmingyuan West Road No. 2, Haidian District, Beijing 100193, P. R. China
4. College of Environment and Safety Engineering, North University of China, Taiyuan 030051, P. R. China