1. Department of Physics and Astronomy, University of California Irvine, Irvine, California 92697, United States
2. Computer Network Information Centre, Chinese Academy of Sciences, Beijing, 100190, P. R. China
3. University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
4. BASF Corporation, Iselin, New Jersey 08830, United States
5. BASF Corporation, Beachwood, Ohio 44122, United States