Two-level system with a thermally fluctuating transfer matrix element: Application to the problem of DNA charge transfer

TL;DR

This paper models DNA charge transfer as thermally-assisted tunneling influenced by fluctuating base pair alignments, revealing two characteristic time scales consistent with experimental data.

Contribution

It introduces a two-level system model with a fluctuating transfer matrix element to describe DNA charge transfer, incorporating thermal fluctuations and rate-limiting alignment effects.

Findings

Charge transfer exhibits two distinct time scales.

The model aligns with experimental observations.

Thermal fluctuations significantly influence tunneling rates.

Abstract

Charge transfer along the base-pair stack in DNA is modeled in terms of thermally-assisted tunneling between adjacent base pairs. Central to our approach is the notion that tunneling between fluctuating pairs is rate-limited by the requirement of their optimal alignment. We focus on this aspect of the process by modeling two adjacent base pairs in terms of a classical damped oscillator subject to thermal fluctuations as described by a Fokker-Planck equation. We find that the process is characterized by two time scales, a result that is in accord with experimental findings.