Holstein polaron in the presence of disorder

TL;DR

This paper introduces the Inhomogeneous Momentum Average (IMA) method to study single polaron problems with disorder, revealing complex inhomogeneous and retarded responses that align with experimental observations.

Contribution

The paper develops and validates the IMA method for disordered polaron systems, enabling analysis of inhomogeneous electron-phonon interactions with greater simplicity and accuracy.

Findings

Electron-phonon coupling induces inhomogeneous, retarded potentials.

IMA accurately matches Diagrammatic Monte Carlo results.

Inhomogeneities affect STM imaging through nonlocal, retarded responses.

Abstract

Non-local, inhomogeneous and retarded response observed in experiments is reproduced by introducing the Inhomogeneous Momentum Average (IMA) method to study single polaron problems with disorder in the on-site potential and/or spatial variations of the electron-phonon couplings and/or phonon frequencies. We show that the electron-phonon coupling gives rise to an additional inhomogeneous, strongly retarded potential, which makes instant approximations questionable. The accuracy of IMA is demonstrated by comparison with results from the approximation free Diagrammatic Monte Carlo (DMC) method. Its simplicity allows for easy study of many problems that were previously unaccessible. As an example, we show how inhomogeneities in the electron-phonon coupling lead to nonlocal, retarded response in scanning tunneling microscopy (STM) images.