1. Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario LBS 4M1, Canada
2. Laboratory of Computational and Theoretical Chemistry, Faculty of Chemistry, University of Havana, Havana, Cuba
3. Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281 (S3), 9000 Gent, Belgium
4. Center for Molecular Modeling, Ghent University, Technologiepark 903, 9052 Zwijnaarde, Belgium