1. JILA, National Institute of Standards and Technology and University of Colorado Boulder, Boulder, CO 80309, United States
2. Quantum
Theory Project, Departments of Chemistry and Physics, University of Florida, Gainesville, FL 32611, United States
3. Department
of Chemistry, University of Colorado, Boulder, CO 80302, United States
4. Chemical
Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439, United States
5. Computation
Institute, The University of Chicago, Chicago, IL 60637, United States