Oxygen induced segregation of copper to Ag/Cu(1 0 0) surface

We have studied oxygen induced segregation of copper on Ag/Cu(1 0 0) surface using DFT methods. We calculated the energetics for the ideal and reconstructed copper surfaces having a layer of silver in different depths of the slab with different oxygen coverages. With no oxygen present, the preferred location of silver atoms was the topmost layer. At the coverage 0.5 ML and higher our results support the experimental observation of Hirsimنki et al. that copper replaces silver in the topmost layer of the surface when the surface is in contact with oxygen [M. Hirsimنki, M. Lampimنki, K. Lahtonen, I. Chorkendorff, M. Valden, Surf. Sci. 583 (2005) 157].