Hiroyuki Takenaka1, Ilya Grinberg2, Andrew M Rappe3. 1. Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, NE, USA. 2. Department of Chemistry, Bar-Ilan University, Ramat Gan, Israel. 3. Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA. rappe@sas.upenn.edu.