1. Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48, Vassileos Constantinou Ave, Athens 116/35, Greece
2. Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto 606-01, Japan
3. Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-77, Japan
4. Department of Material Science, Faculty of Science, Himeji Institute of Technology, 1475-2 Kanaji, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan