We develop a simple local-field-effect theory in order to calculate the polarization near the surface and the surface dielectric response of crystals. We obtain a surface-induced anisotropy in all the optical properties of cubic crystals. A calculation of the reflectance anisotropy of a Ge(110) surface is in good agreement with recent measurements.

• Received 1 April 1985

DOI:https://doi.org/10.1103/PhysRevLett.55.1192