First-principles study of the layering at the free liquid Sn surface

Abstract

Molecular-dynamics simulations of the free surface of liquid Sn have been performed using first-principles methods. The ionic density profile shows a stratification extending several atomic diameters into the bulk. The calculated reflectivity shows a marked maximum at a wave-vector transfer of the order of the inverse nearest-neighbor distance and whose origin is related to the surface layering. Moreover, we also find another weak broad maximum at much smaller wave-vector transfers. We analyze and discuss the origin of this anomalous feature, which is also exhibited by the experimental data.