Dynamical properties of the Si(553)-Au nanowire system

Abstract

The lattice dynamics of the Si(553)-Au surface is modeled from first principles according to different structural models. A multitude of surface-localized phonon modes is predicted. As a general rule, low-energy modes are associated to vibrations within the Au chain, while high-energy modes are mostly localized at the Si step edge. The presence of model specific displacement patterns allows to identify the structural models compatible with the measured spectra at low and at room temperature. Our atomistic models within density functional theory allow to assign spectroscopic signatures available from the literature to displacement patterns, and to explain the activity of nominally Raman silent modes.