First principles calculation of oxygen adsorption and reconstruction of Cu(110) surface

We have carried out first principles calculations for the adsorption of oxygen on the Cu(110) surface. The stable adsorption sites of chemisorbed atomic oxygen on the clean unreconstructed surface are investigated at 1/6, 1/2, 2/3 and 1 monolayer (ML) coverage. For the low coverage case, the O atom is found to be most stable in a position close to the fourfold hollow site. At half coverage, the most stable structure is – in agreement with experiment – the (2×1) pairing row reconstruction. The electronic properties of the (2×1) reconstruction are evaluated and discussed in detail. To study the growth of the (2×1) added row reconstruction an investigation of the diffusion pathways of Cu and O adatoms on the surface is presented. The diffusion barriers for O adatoms are found to be 150 meV in the [1 1 ̄ 0] and 300 meV in the [001] direction. For Cu adatoms, both the “jump” mechanism, by which diffusion parallel to the [001] troughs is accomplished, and the “exchange” mechanism, which is responsible for the diffusion parallel to the [1 1 ̄ 0] direction, are investigated, and the diffusion barriers are evaluated. We find that the exchange mechanism has a slightly higher barrier (350 meV) than the jump mechanism (230 meV). The process responsible for the growth of Cu–O–Cu chains parallel to the [001] direction is discussed.