1. Department of Chemistry, The University of Georgia, Athens, Georgia 30602
2. Department of Physics, Villanova University, Villanova, Pennsylvania 19085
3. Department of Chemistry, University of the Free State, 9300 Bloemfontein, Republic of South Africa
4. Department of Chemistry and Center for Theoretical and Computational Chemistry, University of Tromso̷, N-9037 Tromso̷, Norway