Analysis of Low-Energy-Electron Diffraction Intensity Profiles from the (100) and (111) Faces of Nickel

Low-energy-electron-diffraction (LEED) intensity profiles are calculated for the (100) and (111) faces of nickel and compared with experimental measurements. An electron—ion-core potential of the conventional muffin-tin form is used in this work. The inner potential $V_0$ is determined from work-function measurements using the position of the $d$-wave resonance to locate the approximate (within 1-2 eV) position of the Fermi level. This value of $V_0$ gives a good placement of peak positions for electron energies ≤240 eV for both faces. A constant mean-free-path parameter of ${\lambda }_{\mathrm{ee}}=8\mathrm{}$ Å is used to parametrize the imaginary part of the one-electron proper self-energy. Five partial-wave components are used to describe the vibronically renormalized electron—ion-core elastic-scattering vertex. The results adequately describe both the absolute intensities and the shapes of the experimental intensity profiles for the (100) face but only the shapes of the experimental intensity profiles for the (111) face. Analysis of the data indicates that the upper layer spacing is the same as the bulk value (to within ∼ 0.1 Å) for both faces.