1. Wide Bandgap Semiconductor Group, National Institute for Material Science, Tsukuba 305-0044, Japan
2. Center for Advanced Intelligence Project (AIP), RIKEN, 1-4-1 Nihombashi, Chuo-ku, Tokyo 103-0027, Japan
3. International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
4. Division of Applied Physics, Faculty of Pure and Applied Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan
5. Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa, Chiba 277-8561, Japan
6. Research and Services Division of Materials Data and Integrated System, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
7. Materials Sciences Research Center, Japan Atomic Energy Agency, 1-1-1, Kouto, Sayo, Hyogo 679-5148, Japan