Electronic structure of the c(2 × 2)O/Cu(001) system

Abstract

The locally self-consistent real-space multiple-scattering technique has been applied to calculate the electronic structure and chemical binding for the c(2 × 2) O overlayer on Cu(001), for a set of values of dO-cu1, the height of O above the fourfold hollow sites, as proposed from experiment. The O-Cu bond is found to have a mixed ionic-covalent character in all cases. However, the electron charge transfer from the metal surface to O depends strongly on dO-cu1 and is traced to the strength of the long-range Coulomb interaction. A competition between the hybridization of Cu-dxz states with O-px/py states and that of Cu-dx2-y2 states with O-pz states, is shown to control the modification of the electronic structure as O atoms approach the Cu(001) surface. Further, the O valence electronic charge density is found to be anisotropic and nonmonotonically dependent on dO.cu1. We compare the electronic structure of the c(2 × 2) 0 overlayer on Cu(001) and Ni(001), to draw conclusions about their relative stability.