1. Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, Texas 77842-3012, United States
2. Laboratory for Molecular Simulation, Texas A&M University, P.O. Box 30012, College Station, Texas 77843-3255, United States
3. Institute of Chemistry, Academia Sinica, Taipei, Taiwan 115, Republic of China
4. Department of Chemistry, Texas A&M University at Qatar, P.O. Box 23874, Doha, Qatar