[1] Univ Copenhagen, Dept Chem, HC Orsted Inst, DK-2100 Copenhagen, Denmark
[2] Lund Univ, Ctr Chem, Dept Theoret Chem, S-22100 Lund, Sweden
[3] Aarhus Univ, Dept Chem, DK-8000 Aarhus C, Denmark
[4] Forschungszentrum Karlsruhe, Inst Nanotechnol, D-76021 Karlsruhe, Germany