1. Department of Chemistry, Niigata University, Ikarashi Nino-cho 8050, Niigata
950-2181, Japan
2. Physics
Division, National Center for Theoretical Sciences, Hsin-Chu,
300 Taiwan
3. Institute of
Atomic and Molecular
Science, Academia Sinica, Taipei 10617,
Taiwan
4. Department of Chemistry,
Graduate
School of Science, Tohoku University, Sendai
980-8578, Japan