First-principles phonon and multiple-scattering electron-energy-loss-spectra studies of Cu(111) and Ag(111).

Abstract

Parameter-free first-principles phonon calculations are used in conjunction with multiple-scattering electron-energy-loss calculations to reveal new localized modes on Cu(111) and Ag(111). The discovery of these z-polarized localized modes along \ensuremath{\Gamma}\ifmmode\bar\else\textasciimacron\fi{} M\ifmmode\bar\else\textasciimacron\fi{} and \ensuremath{\Gamma}\ifmmode\bar\else\textasciimacron\fi{} K\ifmmode\bar\else\textasciimacron\fi{} provides for the first time good agreement between theory and all the existing helium-atom-scattering and electron-energy-loss experimental results. The new results indicate that it is not necessary to evoke exotic models such as anomalous surface dynamical effects on these densely packed surfaces.