1. Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
2. Center for Non-Linear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
3. Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
4. Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States