Electron motion in a Holstein molecular chain in an electric field

TL;DR

This paper models charge motion in a Holstein molecular chain under an electric field, revealing conditions for polaron movement, oscillations, and Bloch oscillations without dissipation, highlighting the effects of chain discreteness.

Contribution

It introduces a model for polaron dynamics in a Holstein chain under electric fields, detailing oscillation behaviors and conditions for Bloch oscillations.

Findings

Polaron moves uniformly with small shape oscillations in weak fields.

Critical electric field causes polaron to oscillate at Bloch frequency.

Polaron can exhibit Bloch oscillations while retaining shape.

Abstract

A charge motion in an electric field in a Holstein molecular chain is modeled in the absence of dissipation. It is shown that in a weak electric field a Holstein polaron moves uniformly experiencing small oscillations of its shape. These oscillations are associated with the chain's discreteness and caused by the presence of Peierls-Nabarro potential there. The critical value of the electric field intensity at which the moving polaron starts oscillating at Bloch frequency is found. It is shown that the polaron can demonstrate Bloch oscillations retaining its shape. It is also shown that a breathing mode of Bloch oscillations can arise. In all cases the polaron motion along the chain is infinite.