Thermal effect on the dielectric function and small polaron hopping conduction in organic molecular crystals

A Green function formalism is applied to study the dielectric function spectra and the small polaron hopping conduction in organic molecular crystals. In the calculations, the electron–phonon interaction is considered within the Hartree–Fock approximation, and the temperature effect is taken into account. Our theoretical approach is based on the polar electron–phonon interaction (Fröhlich type) to characterize the non-degenerate polaron gas, with the assumption of the electronic hopping between the first-neighbor.