1. Physics Department of Shanghai Jiao Tong University, Shanghai 200030, P. R. China
2. State Key Laboratory of Scientific and Engineering Computing, Institute of Computational Mathematics and Scientific Engineering Computing, Academy of Mathematics and System Sciences, Academia Sinica, P.O. Box 2719, Beijing 100080, P. R. China
3. Department of Physics, Shaoxing College of Arts and Sciences, Shaoxing 312000, P. R. China
4. Physics Department of Zhejiang Normal University, Jinghua 321004, P. R. China
5. School of Mathematics, The University of New South Wales, Sydney, NSW 2052, Australia