Oscillatory lattice relaxation at metal surfaces

It was shown decades ago within the jellium model that the redistribution o f the itinerant electrons at a simple metal surface results in damped elect ron 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 c onfirm a long-standing and widespread speculation, but further provide a si mple physical picture for yet another common phenomenon in lattice relaxati on: The Fridel oscillations in electron density contribute to drive the ion s to relax in an oscillatory fashion, as evidenced by a corroborative compa rison between theory and experiment for Mg(10 (1) over bar 0). [S0163-1829( 99)08203-X].