1. School of Chemistry, University of Nottingham, Nottingham NG7 2RD, U.K.
2. Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S Cass Avenue, Lemont, Illinois 60439, United States
3. Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, United States
4. Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo, P.O.
Box 1033, Blindern, Oslo N-0315, Norway