1. Department of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland
2. Department of Chemistry, University of Basel, 4003 Basel, Switzerland
3. Institute of Nanotechnology, Karlsruhe Institute of Technology, P.O. Box 3640, 76021 Karlsruhe, Germany
4. Institut für Theoretische Festkörperphysik
5. Institut für Theorie der Kondensierten Materie