1. Institute of Biomedical Research, Yunnan University, Kunming, Yunnan 650500, P. R. China
2. Department of Chemistry and Chemical Biology, McMaster University, Hamilton ONL8S4M1, Canada
3. Graduate School of System Informatics, Kobe University, Nada-ku, Kobe, Hyogo 657-8501, Japan
4. Research Computing Center, University of North Carolina, Chapel Hill, North Carolina 27599-3420, United States
5. Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, United States