1. Program in Computational & Molecular Biophysics, Washington University School of Medicine, Saint Louis, Missouri 63110, United States
2. Center for Computing Research, Sandia National Laboratories, Albuquerque, New Mexico 87123, United States
3. Department of Chemistry, Washington University in Saint Louis, Saint Louis, Missouri 63130, United States
4. Department of Biochemistry & Molecular Biophysics, Washington University School of Medicine, Saint Louis, Missouri 63110, United States