1. Nanotechnology Research Institute and Technical Center, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, Tsukuba, Ibaraki 305-8565, Japan, Research Institute of Computational Sciences, AIST, Umezono 1-1, Tsukuba, Ibaraki 305-8568, Japan, and Department of Material and Life Science, Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita, Osaka 565-0871, Japan