1. Computational Chemical Biology, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, Departments of Chemistry and of Chemical Engineering and Materials Science, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, and Environmental Molecular Science Institute and Department of Chemistry, University of CaliforniaIrvine, Irvine, California 92697-2025.