1. School of Mathematics, University of Bristol, Bristol BS8 1TW, United Kingdom
2. Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, USA
3. School of Chemistry, Cardiff University, Cardiff CF10 3AT, United Kingdom
4. Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, and Department of Chemistry, University of Crete, Iraklion 711 10, Crete, Greece