Charge migration mechanisms in the DNA at finite temperature revisited; from quasi-ballistic to subdiffusive transport

TL;DR

This paper revisits charge migration in DNA, analyzing mechanisms across temperature ranges, and finds that at low temperatures transport is quasi-ballistic, while at high temperatures it is fluctuation-assisted, challenging the polaronic model.

Contribution

The study introduces a temperature-dependent analysis of charge transport mechanisms in DNA using the Peyrard-Bishop-Holstein model, highlighting the dominance of fluctuation-assisted transport at high temperatures.

Findings

At low temperatures, charge transport is quasi-ballistic.

Polaron formation is unlikely across a broad temperature range.

High-temperature transport is dominated by fluctuation-assisted mechanisms.

Abstract

Various charge migration mechanisms in the DNA are studied within the framework of the Peyrard-Bishop-Holstein model which has been widely used to address charge dynamics in this macromolecule. To analyze these mechanisms we consider characteristic size and time scales of the fluctuations of the electronic and vibrational subsystems. It is shown, in particular, that due to substantial differences in these timescales polaron formation is unlikely within a broad range of temperatures. We demonstrate that at low temperatures electronic transport can be quasi-ballistic. For high temperatures, we propose an alternative to polaronic charge migration mechanism: the fluctuation-assisted one, in which the electron dynamics is governed by relatively slow fluctuations of the vibrational subsystem. We argue also that the discussed methods and mechanisms can be relevant for other organic macromolecular systems, such as conjugated polymers and molecular aggregates.