DIRECT LOW-ENERGY ELECTRON-DIFFRACTION ANALYSIS OF C(2X2)O/NI(100) INCLUDING SUBSTRATE RECONSTRUCTION

A direct low-energy electron-diffraction (LEED) method for complex adsorption structures is described as an inversion of tensor LEED and applied to the adsorption system c(2×2)O/Ni(100), saving computer time by an order of magnitude. Oxygen resides in hollow sites; the first substrate layer distance is expanded and the second substrate layer reconstructs into a buckled layer. The direct method resolves the adsorption height as well as the adsorbate-induced substrate relaxation and reconstruction. The structure found compares very well to the results of a conventional analysis within the usual limits of error. Generally, the method can be expected to provide rapid access to complicated adsorption structures described by an increased number of parameters which cannot be handled in a usual trial and error procedure because of computational reasons. © 1990 The American Physical Society.