1. Nano-Science Center and Department of Chemistry, University of Copenhagen, 2100 Copenhagen Ø, Denmark
2. Department of Physics, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
3. Synopsys, Inc., Fruebjergvej 3, 2100 Copenhagen, Denmark
4. Department of Applied Mathematics and Statistics and Institute for Advanced Computational Science, Stony Brook University, Stony Brook, New York 11794, USA