1. Supercomputational Modeling and Simulation Laboratory (SMSL), Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul, Korea 130-650, Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, Department of Chemistry, Hanyang University, Haengdangdong 17, Sungdongku, Seoul, Korea 133-791, and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706