Optical and acoustic polaron formation: Dynamic matrix approach (DMA)

Abstract

This paper presents an all-coupling approach (dynamic matrix approach (DMA)) for the description of polaron regimes. The model under investigation is based on an ionic crystal in which the electron-phonon coupling is modified by thermal excitations. The internal displacements of cations and anions as well as the resulting spontaneous polarization highlights the contributions of acoustic and optical phonon modes to Polaron formation. The electron-phonon Hamiltonian is therefore modified and a new quasi-particle is formed from the simultaneous interaction of the charge carrier with both acoustic and optical phonon modes. From this model, we gauge our method by comparison of the derived characteristics to well-known results (weak- and strong-coupling limit). It is observed that, the pyroelectric effect enhances the electron-phonon coupling and the combined contribution of both acoustic and optical modes leads to a composite polaron with a lager inertia.