Oxygen adsorption on Al (111) surface interstitial site calculated by density functional theory

The adsorption possibilities of oxygen atoms at Al (111) surface for different oxygen atom coverages (Theta) from 0.25 to 1ml have been studied using first principles based on density functional theory with generalized gradient approximation. The results show that the interstitial sites on Al (111) surface are relatively stable, in which binding energies are 0.6 similar to 1 eV/ atom lower than those on surface face centered cubic (fcc) sites for the different coverages. The binding energy and work function of the oxygen-adsorbed surface increase with the oxygen atom coverage. Moreover, the oxygen atom at one tetrahedral site of Al (111) subsurface becomes more and more unstable with the decrease of the coverage, and it moves up to the Al (111) surface hexagonal close packed (hcp) site at Theta = 0.25. All the octahedral absorption sites are also unstable in relatively lower coverages (Theta = 0.5 and 0.25). The bond length and overlap population between Al and O, including the relaxation effects on the oxygen atom coverage are discussed. Copyright (C) 2010 John Wiley & Sons, Ltd.