1. Research Institute for Computational Sciences (RICS), National Institute of Advanced Industrial Science and Technology (AIST), Central-2, Umezono 1-1-1, Tsukuba 305-8568, Japan, and Nanotechnology Research Institute (NRI), National Institute of Advanced Industrial Science and Technology (AIST), Central-5, Higashi 1-1-1, Tsukuba 305-8565, Japan