1. Department of Physics Universidad de La Frontera Casilla Chile
2. Center for the Development of Nanoscience and Nanotechnology Santiago de Chile Chile
3. School of Engineering Central University of Chile Santiago Chile
4. Los Eucaliptus 1189 Temuco Chile
5. Institut für Theoretische Physik Technische Universität Dresden Dresden Germany
6. D‐35759 Driedorf Germany