1. Jülich Supercomputing Centre, Institute for Advanced Simulation, Forschungszentrum Jülich, 52425 Jülich, Germany
2. AIDAS, 52425 Jülich, Germany
3. Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
4. Department of Physics, RWTH Aachen University, 52056 Aachen, Germany