作者机构:[1]Yunnan Key Laboratory of Nanomaterials & Technology, Yunnan University, Kunming 650091, China
相关基金:Project supported by the National Natural Science Foundation of China (Grant No. 50862009), the New Century Excellent Talents in University of the Ministry of Education, China (Grant No. NCET-04-0915), and the Natural Science Foundation of Yunnan Province of China (Grant No. 2005E007M).
Acknowledgments The authors thank Zhao Zong-Yan for the helpful discussions and the High Performance Computer Centre of Yunnan University for providing software and hardware support in our calculations.