Transport through a molecular quantum dot in the polaron crossover regime

TL;DR

This paper develops a non-perturbative method using non-equilibrium Green functions to analyze electron transport through a molecular quantum dot with intermediate electron-phonon coupling, revealing spectral features influenced by polaron correlations.

Contribution

It introduces a novel non-perturbative scheme in the polaron representation to study transport in molecular quantum dots at intermediate coupling regimes.

Findings

Spectral function peaks sharpen with increased tunneling coupling.

Polaron cloud correlations significantly affect spectral features at higher temperatures.

Potential experimental signatures in current-voltage characteristics are discussed.

Abstract

We consider resonant transport through a molecular quantum dot coupled to a local vibration mode. Applying the non-equilibrium Green function technique in the polaron representation, we develop a non-perturbative scheme to calculate the electron spectral function of the molecule in the regime of intermediate electron-phonon coupling. With increasing tunneling coupling to the leads, correlations between polaron clouds become more important at relatively high temperature leading to a strong sharpening of the peak structure in the spectral function. The detection of such features in the current-voltage characteristics is briefly discussed.