基金This work is supported by the National Natural Science Foundation of China (No.21373064), the Program for Innovative Research Team of Guizhou Province (No.QKTD[2014]4021), and the Natural Sci- entific Foundation from Guizhou Provincial Department of Education (No.ZDXK[2014]IS). All the calculations were performed at Guizhou Provincial High- Performance Computing Center of Condensed Mate- rials and Molecular Simulation in Guizhou Education University.