作者机构:[1]College of Mathematics and Statistics, Chong Qing University, Chong Qing 401331,China., [2]Institute of Applied Physics and Computational Mathematics, P.O. Box 8009, Beijing 100088, China., [3]College of Mathematics and Statistics, Central South University, Changsha 410075, China.
相关基金:Acknowledgments The authors thank for Professor Dong Zhao for his valuable discussions. This work is partially supported by NNSF of China (Grant No. 11071258/A0110,90820302), Tianyuan Foundation of NSF (Grant No. 11126079) and CPSF (Grant No. 2013M530559).