Influence of Small Impurities on Low-Energy Electron Dynamics in   Two-Dimensional Microscopic Bounded Region
  In order to give some insight into a role of small impurities on the electron motion in microscopic devices, we examine from a general viewpoint, the effect of small obstacles on a particle motion at low energy inside microscopic bounded regions. It will be shown that the obstacles disturb the electron motion only if they are weakly attractive. 
T. Shigehara, M. Yokoyama, H. Mizoguchi, T. Mishima (Saitama U) and   Taksu Cheon (Kochi Tech)