III-V(110) surface dynamics from anab initiofrozen-phonon approach

We have applied the ab initio pseudopotential frozen-phonon approach to study phonon frequencies and eigenmodes for III-V(110) surfaces. For GaAs our results at the Γ¯ and X¯ points are in good agreement with data from recent high-resolution electron-energy-loss spectroscopy and He-scattering experiments. In the energy range of the controversially discussed ${\mathit{A}}_1$ phonon we observe an eigenmode with large atomic amplitudes at the surface, which, however, is mixed with bulk states. In order to investigate the chemical trend, additional calculations for surface Γ¯ phonons of InAs, GaP, and InP are presented. We observe a rather similar dynamical behavior for all these surfaces with modifications mainly due to the different masses of group-III and -V elements.