1. National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0047, Japan
2. State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, P. R. China
3. Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan
4. Department of Materials Science and Engineering, Ibaraki University, Hitachi, Ibaraki 316-8511, Japan
5. Aisin Corporation, Kariya, Aichi 448-8650, Japan