Oscillatory lattice relaxation at metal surfaces

It was shown decades ago within the jellium model that the redistribution of the itinerant electrons at a simple metal surface results in damped electron density oscillations propagating into the bulk (Friedel oscillations). Using self-consistent density-functional theory calculations, we show that pronounced Friedel oscillations still exist at such surfaces even when the effects of the ionic cores are included explicitly. Our findings not only confirm a long-standing and widespread speculation, but further provide a simple physical picture for yet another common phenomenon in lattice relaxation: The Fridel oscillations in electron density contribute to drive the ions to relax in an oscillatory fashion, as evidenced by a corroborative comparison between theory and experiment for Mg(1010).