O adsorption and incipient oxidation of the Mg(0001) surface

TL;DR

This study uses first principles calculations to investigate the initial oxidation process of Mg(0001), revealing oxygen incorporation below the surface at low coverages and clustering behavior at higher coverages, aligning with experimental data.

Contribution

It provides detailed atomic-scale insights into oxygen adsorption and oxidation stages of Mg(0001), including preferred sites and structural configurations, using first principles density functional theory.

Findings

O incorporates below the surface at low coverages

On-surface binding increases with oxygen coverage

Oxygen tends to form clusters and islands at higher coverages

Abstract

First principles density functional calculations are used to study the early oxidation stages of the Mg(0001) surface for oxygen coverages 1/16 <= Theta <= 3 monolayers. It is found that at very low coverages O is incorporated below the topmost Mg layer in tetrahedral sites. At higher oxygen-load the binding in on-surface sites is increased but at one monolayer coverage the on-surface binding is still about 60 meV weaker than for subsurface sites. The subsurface octahedral sites are found to be unfavorable compared to subsurface tetrahedral sites and to on-surface sites. At higher coverages oxygen adsorbs both under the surface and up. Our calculations predict island formation and clustering of incorporated and adsorbed oxygen in agreement with previous calculations. The calculated configurations are compared with the angle-scanned x-ray photoelectron diffraction experiment to determine the geometrical structure of the oxidized Mg(0001) surface.