1. Group of Theoretical Chemistry, Department SBG, Hasselt University, Agoralaan, Gebouw D, B-3590 Diepenbeek, Belgium, School of Chemistry, Physics and Earth Sciences, Flinders University, GPO Box 2100, Adelaide SA 5001, Australia, Centre for Molecular Simulation, Swinburne University of Technology, PO Box 218, Hawthorn, Vic 3122, Australia, and CSIRO Molecular Science, Private Bag 10, Clayton South MDC, Vic 3169, Australia, and School of Chemistry, Monash University, Clayton, Vic 3168, Australia