1. Dipartimento di Chimica “Giacomo Ciamician,” Università degli Studi di Bologna, Via Selmi 2, I-40126 Bologna, Italy
2. Institut für Nanotechnologie, Karlsruher Institut für Technologie (KIT), Campus Nord, Postfach 3640, D-76021 Karlsruhe, Germany
3. Center for Theoretical Chemistry, Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA
4. Institut für Physikalische Chemie, Universität Mainz, D-55099 Mainz, Germany