1. Department of Chemistry and Hylleraas Centre for Quantum Molecular Sciences, University of Oslo, P.O. Box 1033 Blindern, Oslo 0315, Norway
2. Department Chemie, Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14, Mainz 55128, Germany
3. ICGM, Université de Montpellier, CNRS, ENSCM, Montpellier 34095 Cedex 5, France