ADSORBATE INDUCED RECONSTRUCTION PHASE P(2X2)O/NI(100)

The adsorption system of p(2 × 2)O/Ni(100) was reinvestigated by a detailed LEED analysis, whereby the purity of the p(2 × 2) phase was controlled by HREELS. Full dynamical calculations were performed allowing for both substrate reconstruction and relaxation which both prove to be essential to yield a satisfying theory-experiment fit. Oxygen resides in the fourfold Symmetrie hollow site at 0.80 Å height above the first substrate layer whose distance from the second layer is expanded by 2.5% compared to the bulk distance. The second substrate layer is considerably buckled by as much as 0.10 Å. The determined adsorption height as well as the surface relaxation are in agreement with the results of semi-empirical total energy calculations and are consistent with a recent structure determination of the c(2 × 2) phase. © 1990.