1. Heidelberg Institute for Theoretical Studies, Heidelberg, Germany
2. Institute of Theoretical Informatics, Karlsruhe Institute of Technology, Engler-Bunte-Ring 8, Karlsruhe 76131, Germany
3. Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1: 76344 Eggenstein-Leopoldshafen, Germany
4. Interdisciplinary Center for Scientific Computing, Heidelberg University, Heidelberg, Germany