1. Department of Materials Science Graduate School of Engineering, Chiba University, 1‐33 Yayoi‐cho, Inage‐ku Chiba 263‐8522 Japan
2. Department of Applied Chemistry, Graduate School of Engineering Hiroshima University, 1‐4‐1 Kagamiyama, Higashi‐Hiroshima Hiroshima 739‐8527 Japan
3. Mazda Motor Corporation, 3‐1 Shinchi, Fuchu‐cho, Aki‐gun Hiroshima 730‐8670 Japan
4. Advanced Materials Laboratory, Advanced Automotive Research Collaborative Laboratory, Graduate School of Engineering Hiroshima University, 1‐4‐1 Kagamiyama, Higashi‐Hiroshima Hiroshima 739‐8527 Japan
5. Quantum Chemistry Division, Graduate School of Science Yokohama City University, 22‐2 Seto, Kanazawa‐ku, Yokohama Kanagawa 236‐0027 Japan