1. Department of Chemistry, the Johns Hopkins University, Baltimore, Maryland 21218, United States
2. Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via G. Moruzzi 13, Pisa I-56124, Italy
3. Fachrichtung Chemie, Universität des Saarlandes, Saarbrücken D-66123, Germany
4. Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo, P.O.
Box 1033, Blindern, Oslo N-0315, Norway
5. Department Chemie, Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14, Mainz D-55128, Germany