1. Department of Chemistry, University of Helsinki, P.O. Box 55, A.I. Virtanens plats 1, FI-00014 University of Helsinki, Finland
2. Molecular Sciences Software Institute, Blacksburg, Virginia 24061, United States
3. Institute of Nanotechnology, KIT, Hermann-von-Helmholtz Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany