1. Department of Chemistry and Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602, Institut für Organische Chemie, Universität Erlangen-Nürnberg, Henkestrasse 42, Erlangen, D-91054, Germany, Department of Physical Chemistry, University of Geneva, 30 quai Ernest-Ansermet, CH-1211, Genève 4, Switzerland, Institut für Physikalische Chemie, Technische Universität Dresden, D-01062 Dresden, Germany, and Department of Chemistry, Texas Lutheran University, Seguin, Texas 78155