Variational Calculation of Low-Energy Electron Diffraction Spectra

Abstract

On the basis of the Lippmann-Schwinger variational theory, an efficient method, called “perturbation-variation method,” for calculating low-energy electron diffraction (LEED) spectra, is developed. The LEED spectra of the (00), (10) and (11) spots from the nickel (100) surface are calculated by adopting the isotropic inelastic scattering model and by using 1) the matrix inversion method, 2) the t -matrix perturbation method and 3) the perturbation-variation method. For the present model, method 1) is exact and methods 2) and 3) are approximations to method 1). It is found that the convergence of method 3) is much faster than that of method 2) for all LEED spectra calculated with various choices of the s-wave phase shift and the imaginary part of the inner potential