A LOW-ENERGY ELECTRON-DIFFRACTION STUDY OF THE MGO(001) SURFACE-STRUCTURE

Low-energy electron diffraction (LEED) beam intensities were measured from the freshly cleaved [in ultrahigh vacuum] MgO(001) surface using beam energy modulation to avoid electrical charging. Dynamic LEED analysis of the data indicates: (1) an interlayer relaxation of (1 +/- 2)% and a rumple of the first layer ions of (5 +/- 2.5)%; (2) a new attenuation model containing no adjustable parameters gives fits to the data that are comparable to those using a constant imaginary optical potential (V(i); (3) a weak dependence of the optimum rumpling on the energy range of the data used. The structure determined in this study is compared to others reported in the literature for this surface, and the effects of lattice vibrations, attenuation length, and number of surface layers treated exactly are considered.