1. Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstrasse 4+6, D-53115 Bonn, Germany
2. Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45413 Mülheim an der Ruhr, Germany
3. Department of Chemistry, KU Leuven, Celestijnenlaan 200F, bus 2404, B-3001 Heverlee, Belgium