1. Science and Technology Department; IBM Research - Zürich; Säumerstrasse 4 8803 Rüschlikon Switzerland
2. Chemie Departement; University of Zurich; Winterthurerstrasse 190 8057 Zürich Switzerland
3. Institut für Theoretische Physik; TU Wien - Vienna University of Technology; Wiedner Haupstrasse 8-10 Vienna 1040 Austria