ADSORPTION-INDUCED RELAXATION OF NI(001)-C(2X2)-O

Comparisons between full-potential, spin-polarized, total-energy calculations with a low-energy electron diffraction (LEED) intensity analysis for the adsorbed system Ni(001)-c(2×2)-O suggest the importance of bonding between oxygen and the second-layer nickel atom below it. By fixing the associated bond length, we are able to explain the results of a new multilayer LEED analysis which reduces the spacing between the oxygen and the first nickel layer below all previous determinations to 0.750.04 and increases the spacing of the first two nickel layers from the bulk value by 5.7% to 1.860.02. Differences between LEED and surface extended x-ray-absorption fine-structure spectroscopy structure parameters are noted. © 1990 The American Physical Society.