1. Department of ChemistrySchool of ScienceTokyo Institute of Technology Ookayama, Meguro-ku Tokyo 152-8551 Japan
2. Center for Computational SciencesUniversity of Tsukuba Tennodai Tsukuba 305-8577 Japan
3. Present address: Department of Electrical and Electronic EngineeringGraduate School of EngineeringKobe University Rokkodai, Nada-ku Kobe 657-8501 Japan