Reconstruction of the (100) surfaces of Au and Ag.

Abstract

Using first-principles total-energy calculations, together with simulations performed with a Frenkel-Kontorowa model, we show that it is energetically favorable for the top layer of the (100) surface of Au to transform from the ideal square lattice of the (100) surface of a fcc metal to a slightly distorted and contracted hexagonal-close-packed arrangement. The ground-state configuration from our simulation agrees well with experimental observations. The reconstruction is shown to be unfavorable in Ag, which is isoelectronic to Au. The difference in behavior is because the two-dimensional Au layer gains much more energy upon contraction than its Ag counterpart.