The magnitude of the anharmonic contribution to the static dielectric constant

Abstract

It is shown that in ionic crystals the anharmonic contribution to the static dielectric constant can be calculated above the Debye temperature if the derivatives of the dielectric constant with respect to temperature and pressure are known. The necessary data are available for three alkali halides. For these, the anharmonic contribution is found to amount to a few parts per cent of the total lattice contribution.