THEORETICAL INVESTIGATION OF THE ADSORPTION OF ALKALI-METALS ON A CU(111) SURFACE

We present a theoretical investigation, based on ab-initio Hartree-Foc k (HF) and density functional theory (DFT) methods and Cu, cluster mod els, of the adsorption of alkali metals (Li, Na and K) on a (111) copp er surface. Results show that both methods agree, in that lithium adso rbs on a three-fold hollow site and potassium is adsorbed on a top sit e. For sodium the calculations differ: DFT leads to adsorption on a to p site whereas HF calculations predicts adsorption on a three-fold sit e. Local specific interactions responsible for the stabilization of th e alkalis on the different adsorption sites are identified and discuss ed in the framework of DFT. On the other hand, starting from a simple analytic function representing painwise interactions, we present a pro cedure 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.