A new perspective on the Holstein polaron problem

TL;DR

This paper introduces a novel resummed strong-coupling perturbation theory to analyze the Holstein polaron problem, revealing new insights into the band structure at intermediate coupling in one and two dimensions.

Contribution

It presents a new resummed strong-coupling perturbation approach that provides well-converged results for the Holstein polaron band structure at intermediate coupling.

Findings

Polaron band structure deviates from simple tight-binding models at intermediate coupling.

Results are consistent with weak-coupling self-consistent perturbation theory predictions.

The method is effective for phonon frequencies comparable to the hopping integral.

Abstract

The single-polaron band structure of the Holstein model in one and two dimensions is studied using a new form of resummed strong-coupling perturbation theory. Well converged results are obtained for phonon frequencies of the order of the hopping integral and strong to intermediate electron-phonon coupling. The polaron band structure at intermediate coupling is shown to deviate markedly from that of a nearest-neighbor tight-binding model, and is in fact similar in shape to the prediction of weak-coupling self-consistent perturbation theory.