1. Lundbeck Foundation Center for Theoretical Chemistry and Center for Oxygen Microscopy (COMI), Department of Chemistry, University of Aarhus, 8000 Aarhus C (Denmark)
2. Present address: Instituto de Química, UNAM, Circuito Exterior, Ciudad Universitaria, Delegación Coyoacán C.P. 04510, Mexico, D.F. (Mexico), Fax: (+52) 555‐616‐2217
3. Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C (Denmark)
4. Department of Chemistry, University of Copenhagen, 2100 Copenhagen Ø (Denmark)