1. Department of Chemistry and The PULSE Institute, Stanford University, Stanford, California 94305, USA
2. SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
3. Theoretische Chemie, Universität Bielefeld, Postfach 100131, D-33501 Bielefeld, Germany
4. Univ Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251, F-35000 Rennes, France