Surface Diffusion of a Zn Adatom on a Zn(001) Surface:  A DFT Study

Abstract

The adsorption and diffusion of a Zn atom on a Zn(001) surface has been investigated theoretically by using first-principles periodic boundary condition calculations to elucidate the mechanism of crystal growth of zinc in a Zn surface. Three surface models, terrace, step, and kink, of the Zn(001) surface were considered as adsorption sites in the present study. The most stable site in the terrace model was the on-top site, where the zinc adatom is bound to only one zinc atom of the surface. The activation barrier between the on-top site and the next on-top site was negligibly low (the activation energy is 44 meV at the PW91/LANL2DZ level), suggesting that the Zn adatom diffuses easily on the Zn(001) surface. The Zn adatom was more stabilized at the step site (752 meV) and kink site (935 meV) with respect to the on-top site. It was found that the magnitude of 4s−4p orbital mixing of the Zn adatom (hybridization) is strongly related to the binding energy. The mechanism of the adsorption of Zn on Zn(001) surfaces was discussed on the basis of theoretical results.