Reconstruction and subsurface lattice distortions in the (2 1)O-Ni(110) structure: A LEED analysis
LEED analysis of the reconstructed (2 \xd7 1)O-Ni(110) system clearly favors the \u201cmissing row\u201d structure over the \u201csaw-tooth\u201d and \u201cbuckled row\u201d models. By using a novel computational procedure 8 structural parameters could be refined simultaneously, leading to excellent R-factors (RZJ = 0.09, RP = 0.18). The adsorbed O atoms are located 0.2 \xc5 above the long bridge sites in [001] direction, presumably with a slight displacement ( 0.1 \xc5) in [1 0] direction to an asymmetric adsorption site. The nearest-neighbor Ni---O bond lengths (1.77 \xc5) are rather short. The separation between the topmost two Ni layers is expanded to 1.30 \xc5 (bulk value 1.25 \xc5), while that between the second and third layer is slightly contracted to 1.23 \xc5. The third layer is, in addition, slightly buckled (\xb10.05 \xc5). The results are discussed on the basis of our present general knowledge about the structure of adsorbate covered metallic surfaces.