1. Department of Chemistry, Kobe University, Nada-ku, Kobe 6578501 Japan, Computer Center and Department of Chemistry, Tokyo Metropolitan University, 1-1, Minami-Ohsawa, Hachioji-shi, Tokyo 192-0973 Japan/ACT-JST, and Max-Born-Institut, Rudower Chaussee 6, D-12489, Berlin, Germany