1. Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
2. Institute of Chemistry and The Fritz Haber Research Center, The Hebrew University, Jerusalem 91904, Israel
3. Department of Theoretical Physics, J. Stefan Institute, and Department of Physics, Faculty of Mathematics and Physics, University of Ljubljana, 1000 Ljubljana, Slovenia, and Laboratory of Physical and Structural Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20814-0924