1. Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai-mura, Ibaraki-ken 319-11, Japan, and Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-77, Japan
2. The NET Team, Max-Planck-Institute für Plasmaphysik, Boltzmannstrasse 2, D-85748 Garching by Munich, Germany
3. Computer Chemistry Center, Institut für Organische Chemie der Universität Erlangen-Nürnberg, Henkestrasse 42, D-91045 Erlangen, Germany