1. Department of Chemistry and
Chemical Biology, Cornell University, Ithaca,
New York 14853, United States
2. Computer Science and Mathematics
Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States, and Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996,
United States
3. Department
of Chemistry and
Biochemistry and the Molecular Biophysics Program, University of Colorado, Boulder Colorado 80309-0215, United States