1. Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
2. School of Computational Sciences, Korea Institute for Advanced Study, Seoul 130-722, Korea
3. School of Engineering, University of Aberdeen, Fraser Noble Building, Aberdeen AB24 3UE Scotland, United Kingdom
4. Erlangen Graduate School in Advanced Optical Technologies, University Erlangen-Nuremberg, D-91058 Erlangen, Germany