1. Center for Computational Materials Science, Institute of Physics, Slovak Academy of Sciences, Bratislava 84511, Slovakia
2. Wigner Research Centre for Physics, Institute for Solid State Physics and Optics, P.O. Box 49, Budapest H-1525, Hungary
3. Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Kobe, Hyogo 657-8501, Japan
4. Institute of Informatics, Slovak Academy of Sciences, Bratislava 845 07, Slovakia
5. Department of Natural Sciences, University of Ss. Cyril and Methodius, Trnava 917 01, Slovakia