1. Department of Chemistry; Cherry L. Emerson Center for Scientific Computation; Emory University; 1515 Dickey Dr. Atlanta Georgia 30322 USA
2. X-ray Crystallography Center; Emory University; 1515 Dickey Dr. Atlanta Georgia 30322 USA
3. U.S. Army Edgewood Chemical Biological Center, APG, MD; 21010-5424 USA