The infrared effective charge in IV-VI compounds. I. A simple one-dimensional model

A simple one-dimensional model of a diatomic chain is used to explain the unusually large values of the transverse effective charge (Z T *) in cubic IV-VI compounds. By using a pseudopotential formalism, the authors have related Z T * to the chemical electronegativity and found good agreement with experiment in both the magnitude of Z T * and in its trend along the series.