Adsorption of oxygen atoms on the Mg3Nd(001) surface

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 oxi...