Effects of electron-phonon coupling range on the polaron formation

TL;DR

This study investigates how the range of electron-phonon coupling influences polaron properties using a variational approach, revealing similarities between local, nearest neighbor, and long-range interactions and identifying unique correlation behaviors.

Contribution

It provides a comparative analysis of polaron features across different electron-phonon coupling ranges, highlighting the effects of coupling range on physical quantities and correlations.

Findings

Long-range and strong nearest neighbor couplings produce similar polaron characteristics.

Intermediate coupling strength shows an upturn in electron-phonon correlation functions.

Physical quantities like energy and spectral weight vary with coupling range and strength.

Abstract

The polaron features due to electron-phonon interactions with different coupling ranges are investigated by adopting a variational approach. The ground-state 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.