The Influence of Phonons on Dielectric Properties of Molecular Crystals

Abstract

In molecular crystals whose inversion centrum does not coincide with that of the molecule, the Hamiltonian of exciton–phonon interaction is a bilinear form in exciton as well as in phonon operators. This leads to the hybridization of excitons and phonons into new excitations. The dielectric constant is analysed in the system of hybrid excitations. The frequency dependence of dielectric constant is analysed numerically for different values of wave vector. A comparison of dielectric constants of molecular crystals with and without phonons is made. It is shown that the presence of phonons changes the trend and shifts the singularity towards higher frequencies. Copyright © 1988 WILEY‐VCH Verlag GmbH & Co. KGaA