Self-consistent approach for spectral properties of single alkali adatoms on Cu(111)

We investigate the nature of the adatom-surface interaction in the adsorption of alkali atoms on Cu(111). Our calculation, exploiting the embedding approach in a density functional theory framework, describes an isolated atom on a metallic surface, which is modeled via a one-dimensional modulated potential. The absence of empirical term in the Hamiltonian guaranties a completely ab initio determination of the electronic properties of the system. The role of the projected energy gap in determining lifetime and binding energy of the adatom resonances is evidenced. On the basis of the electronic properties of the adsorbed alkali atoms the covalent/ionic nature of the bonding with the surface is analyzed.