1. School of Chemistry University of EastAnglia Norwich NR4 7TJ UK
2. Department of Chemistry University of Leuven Celestijnenlaan 200D 3001 Leuven Belgium
3. Laboratory of Theoretical Chemistry Unit of Theoretical and Structural Physical Chemistry NISM (Namur Institute of Structured Matter) University of Namur Rue de Bruxelles, 61 5000 Namur Belgium