拡張Ｈｕｅｃｋｅｌ法を用いた原子変位のあるグラファイト表面の電子密度分布計算

Abstract

We calculated electron density distribution of the graphite surface with an atomic displacement, in order to analyze scanning tunneling microscope (STM) images of ion irradiated graphite surface.The calculation is based on the extended Huckel molecular orbital (EHMO) method. We found that an electronic perturbation in threefold-symmetry which was observed on the ion irradiated graphite surface is reproduced either by the displacement or by the removal of a β atom at the surface. This result shows that a bright spot of STM image does not always locate at the place where an atom exists.