1. Max Planck Institute for Mathematics in the Sciences, Inselstrasse 22, D04103 Leipzig, Germany, Department of Chemistry, Unilever Centre for Molecular Science Informatics, Lensfield Road, Cambridge CB2 1EW, U.K., and Unilever R&D Vlaardingen, Olivier van Noortlaan 120, 3133 AT Vlaardingen, The Netherlands