Dielectric function spectra from a nondegenerate polaron gas

A Green function formalism is employed to perform an analytical calculation of the dielectric function due to an electron–phonon interaction within a Hartree–Fock approximation. Our theoretical approach is based on the polar or Fröhlich type of electron–phonon interaction, with the electronic hopping between the first-neighbor, to characterize the polaron model. Our numerical results for the dielectric function profile show resonant peaks, all of them at lower frequencies than the main one, attributed to the polaron crossover regime between the quasi-free-electrons and the small polarons.