1. Nano-System Computational Science Group, Nano-System Organization Unit, International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
2. CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 333-0012, Japan
3. Photovoltaic Materials Unit, NIMS, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
4. PRESTO, JST, 4-1-8 Honcho, Kawaguchi, Saitama 333-0012, Japan