Effects of electron-phonon coupling range on the polaron formation

Carmine Antonio Perroni

Coherentia-INFM and Dipartimento di Scienze Fisiche, Università Federico II, Napoli

The polaron features are discussed considering electron-phonon interactions with different coupling ranges. Ground state properties are investigated by adopting a variational approach. The energy, the spectral weight, the average kinetic energy, the mean number of phonons, and the electron-lattice correlation function are discussed for the system with coupling to local and nearest-neighbor lattice displacements comparing the results with the long-range case. For large values of the coupling with nearest-neighbor sites, most physical quantities show a strong resemblance with those obtained for the long-range electron-phonon interaction. Moreover, for intermediate values of interaction strength, the correlation function between electron and nearest-neighbor lattice displacements is characterized by an upturn as function of the electron-phonon coupling constant.