1. Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
2. CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, P. R. China
3. Center for Computational Materials Science, Institute of Physics, Slovak Academy of Sciences, 84511 Bratislava, Slovakia
4. Department of Physics, King’s College London, The Strand, London, WC2R 2LS, United Kingdom
5. Institute of Informatics, Slovak Academy of Sciences, 84507 Bratislava, Slovakia