1. Department of Physics, Federal University of Paraná, P.O. Box 19044, 81531-990 Curitiba, Paraná, Brazil
2. Department of Physics, State University of Londrina, P.O. Box 10011, 86057-970 Londrina, Paraná, Brazil
3. Materials Theory Division, Department of Physics and Astronomy, Uppsala University, Box 516, 75121 Uppsala, Sweden
4. Arubedo AB, Slottsbacken 8, 111 30 Stockholm, Sweden