1. Department of Chemistry and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105, Israel.
2. Arnold-Sommerfeld-Center for Theoretical Physics and Center for NanoScience, Ludwig-Maximilians-Universität München, Theresienstraße 37, D-80333 Munich, Germany.
3. Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA.