Surface phonon calculation for Si(111): H(1×1)

Abstract

We present a theoretical study on the surface vibrations in Si(111): H 1×1. We have calculated their dispersion along the borders of the irreducible part of the surface Brillouin zone by diagonalizing the dynamical matrix for a slab composed by 22 atomic planes. It turns out that by fitting only the stretching and bending frequencies of the Si-H bond on the surface we reproduce quite well the dispersion of very recent He-scattering data for the Rayleigh Wave. In particular it displays a rather flat behavior along zone border, quite softened with respect to the bulk band. Finally we discuss recent Electron Energy Loss measurements in the framework of our model