A STEP FROM SURFACE FICTION TOWARDS SURFACE SCIENCE

We discuss the results of density-functional theory calculations on th e adsorption of Na and K adatoms on Al(111). We describe the nature of the adsorbate-adsorbate and adsorbate-substrate interactions, and the mechanism of the formation of a periodic adlayer. The latter is shown to be actuated by surface vacancies and steps. We then discuss the fo rmation energies of and the diffusion at steps, and we draw conclusion s about the expected shape of adatom (and vacancy) islands and about c rystal growth.