作者机构:[1]School of Mathematics and Physics, Dalian Nationalities University, Dalian 116600, China, [2]State Key Laboratory for Material Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Dalian 116024, China
相关基金:supported by National Natural Science Foundation of China( No. 10405005)Acknowledgments The authors would like to thank G. Benstetter, E. Lodermeier, S.-E. 0ng, ZHANG S., XU J. and LI X. for their assistance.