Adsorption of oxygen atoms on the Mg3Nd(001) surface

Abstract

Based on the density functional theory, the stability of three possible Mg3Nd(001) surfaces is investigated, and the structural and electronic properties of O adsorption on the most stable Mg3Nd(001) surface are studied. The calculated results show that the most favorable adsorption site is the (2Nd+Mg) hollow site, and the adsorption energy decreases as the coverage increases. At low coverage O atoms prefer Nd atoms to Mg atoms as nearest neighbors. When the coverage increases to a full monolayer, some O atoms sink into the alloy surface and stay between Nd and Mg atoms. The electronic structures of the adsorption system show that for all coverage the interaction between O and the alloy surface mainly arises from the hybridization of O 2p states and Nd 5d states, while the interaction between Mg 3s states and O 2p states becomes noticeable at the high coverage. The present study reveals that during the initial oxidation stage of the alloy, Nd atoms can get a priority of oxidation, followed by Nd rich oxide film.