1. Institut für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
2. Center for Mathematics Computing and Cognition, Federal University of ABC (UFABC), Avenida dos Estados 5001, Santo André, Brazil
3. Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany