1. Instituto de Ciencia Molecular, Universitat de València, P.O. Box 22085, ES-46071 Valencia, Spain, Department of Physical Chemistry, University of Geneva, 30, q. E. Ansermet, 1211 Genève, Switzerland, Department of Chemistry and Supercomputing Institute, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455-0431, United States, and Department of Chemistry, Katholieke Universiteit Leuven, Belgium