Adsorption of rare-gas atoms on Cu(111) and Pb(111) surfaces by van der Waals-corrected Density Functional Theory

摘要

The DFT/vdW-WF method, recently developed to include the Van der Waalsinteractions in Density Functional Theory (DFT) using the Maximally LocalizedWannier functions, is applied to the study of the adsorption of rare-gas atoms(Ne, Ar, Kr, and Xe) on the Cu(111) and Pb(111) surfaces, at threehigh-symmetry sites. We evaluate the equilibrium binding energies anddistances, and the induced work-function changes and dipole moments. We findthat, for Ne, Ar, and Kr on the Cu(111) surface the different adsorptionconfigurations are characterized by very similar binding energies, while thefavored adsorption site for Xe on Cu(111) is on top of a Cu atom, in agreementwith previous theoretical calculations and experimental findings, and in commonwith other close-packed metal surfaces. Instead, the favored site is always thehollow one on the Pb(111) surface, which therefore represents an interestingsystem where the investigation of high-coordination sites is possible.Moreover, the Pb(111) substrate is subject, upon rare-gas adsorption, to asignificantly smaller change in the work function (and to a correspondinglysmaller induced dipole moment) than Cu(111). The role of the chosen referenceDFT functional and of different Van der Waals corrections, and their dependenceon different rare-gas adatoms, are also discussed.