1. Centre for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, Sem Sælandsvei 26, N-0315 Oslo, Norway
2. Science Institute and Faculty of Industrial Engineering, Mechanical Engineering and Computer Science, University of Iceland, Hjardarhagi 2, VR-III, 107 Reykjavík, Iceland
3. Centre for Materials Science and Nanotechnology, Department of Physics, University of Oslo, Sem Sælandsvei 26, N-0349 Oslo, Norway
4. Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, N-0315 Oslo, Norway