The application of pseudopotentials to low-energy electron diffraction I. Calculation of the potential and `inner potential'

Abstract

We explain how to set up a potential suitable for low-energy electron diffraction (LEED) calculations. It is found that for off-diagonal matrix elements, the exchange contribution must be calculated from the full Hartree-Fock exchange operator and not from the local Slater approximation. The potential has to be transformed into a pseudopotential to obtain good convergence in k space. Some numbers, which include the `inner potential', are presented from calculations on nickel, niobium and graphite. Comparison with experiment shows the potentials to be accurate to within ±2 eV.