Structural and electronic properties of atomic oxygen adsorption on Cu(111) surface: A first-principles investigation

By using the first-principles calculations, we have systematically investigated the adsorption of atomic oxygen on Cu(111) surface for a wide range of coverages Θ (from 0.11 to 1.00 ML) and adsorption sites. We found that the fcc-hollow site is the most stable site for oxygen adsorption. The adsorption energy decreases with increasing oxygen coverage due to the increasing repulsive interaction in the overlayer O adatoms. Except for coverage of 1.00 ML, the oxygen-induced lateral relaxations and bucklings are found in the outermost three Cu layers, and the hillock-like as well as ridge-like bucklings are also found for Θ=0.25 ML and Θ=0.75 ML as well as Θ=0.50 ML, respectively. With an increasing oxygen coverage, the work function increases and the surface dipole moment decreases. Electron transfer from the first layer Cu atoms to O adatoms indicates the O—Cu bond having some degree of ionic character, while the hybridization between O 2p and Cu 3d orbitals implies that it also has some degree of covalence character. Moreover, with the increasing oxygen coverage, more Cu 3d and O 2p states are empty thus weakening the binding of O/Cu(111) system, but increase in the PDOS at the Fermi level. This implies an enhancement in the metallic character of the O/Cu(111) system.