1. Department of Chemistry, Stony Brook University, Stony Brook, NY 11794, USA.
2. Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
3. Department of Chemistry, Wayne State University, Detroit, MI 48202, USA.
4. Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, GA 30322, USA.
5. Chemistry Division, Argonne National Laboratory, Argonne, IL 60439, USA.