A method was proposed, for the simulation of scanning tunnelling microscopic and spectroscopic data, which was applicable at tip-to-surface distances which were of the order of 0.5 to 1nm. It was applied to (100) reconstructed surfaces. Because the vacuum

tails of wave functions could not be accurately described by using linear combinations of atomic orbitals, or pure plane-wave expansion techniques, an attempt was made to describe the tail parts properly by combining this method with calculations of surface electronic states. The improved method was applied to (100) reconstructed surfaces, and the features of the scanning tunnelling microscopic images and scanning tunnelling spectroscopic spectra of (2 x 1) dimer structures were clarified. This method confirmed that experimentally observed c(4 x 2) images really arose from c(4 x 2) structures, and showed how the buckling of dimers was reflected by scanning tunnelling microscopic images.

H.Kageshima, M.Tsukada: Physical Review B, 1992, 46[11], 6928-37