III-V(110) SURFACE DYNAMICS FROM AN AB-INITIO FROZEN-PHONON APPROACH

We have applied the ab initio pseudopotential frozen-phonon approach t o study phonon frequencies and eigenmodes for III-V (110) surfaces. Fo r GaAs our results at the <(Gamma)over bar> and (X) over bar points ar e in good agreement with data from recent high-resolution electron-ene rgy-loss spectroscopy and He-scattering experiments. In the energy ran ge of the controversially discussed A(1) phonon we observe an eigenmod e with large atomic amplitudes at the surface, which, however, is mixe d with bulk states. In order to investigate the chemical trend, additi onal calculations for surface <(Gamma)over bar> phonons of InAs, Gap, and InP are presented. We observe a rather similiar dynamical behavior for all these surfaces with modifications mainly due to the different masses of group-III and -V elements.