Theoretical investigation of the adsorption of alkali metals on a Cu(111) surface

We present a theoretical investigation, based on ab-initio Hartree-Fock (HF) and density functional theory (DFT) methods and Cu, cluster models, of the adsorption of alkali metals (Li, Na and K) on a (111) copper surface. Results show that both methods agree, in that lithium adsorbs on a three-fold hollow site and potassium is adsorbed on a top site. For sodium the calculations differ: DFT leads to adsorption on a top site whereas HF calculations predicts adsorption on a three-fold site. Local specific interactions responsible for the stabilization of the alkalis on the different adsorption sites are identified and discussed in the framework of DFT. On the other hand, starting from a simple analytic function representing painwise interactions, we present a procedure to obtain the surface corrugations, obtaining good descriptions of its characteristic features such symmetry, position of the minima, and saddle points. (C) 1997 Elsevier Science B.V.