Calculations of low-energy electron diffraction intensities from the polar faces of ZnO

If it is assumed that surface compounds obtained by gas adsorption on metal single crystals faces, are formed by adsorption of atoms on the “sites” of an undisturbed substrate, or of a slightly disturbed substrate, one is lead also to assume that the structures of surface compounds have high symmetries. For well-defined coincidence mesh between the surface compound and the substrate, by applying the 2D space groups (with or without a colored character), information can be obtained concerning the distribution of the adsorbed atoms, or the reconstruction of the substrate. In order to be able to go as far as a complete model, it is necessary to know the concentration of the adsorbed atoms accurately. The hypothesis of a high symmetry has been applied to simple surface compounds: the models of the structures which have been obtained are compared with previously proposed models.