Surface phonon dispersion on Cu(110): a comparison of experiment and theory

The surface-phonon frequencies of the open (110) surface of Cu have been investigated by means of force-constant models. Agreement with experiment is achieved by introducing a surface stress normal to the surface pointing toward the crystal. This force accounts for the charge redistribution which gives rise to the observed contraction of the surface interlayer spacing. In the ΓY direction, where the nearest neighbors do not lie on the surface, a weakening of the surface radial force constants is not necessary as for the (111) surface. The model used explains quite satisfactorily the three modes observed experimentally.