Electronic localization at mesoscopic length scales: different definitions of localization and contact effects in a heuristic DNA model

TL;DR

This study explores electronic transport in model DNA molecules, analyzing localization properties and contact effects, revealing size-independent localization in the thermodynamic limit and addressing discrepancies in experimental results.

Contribution

It introduces a detailed tight-binding model including backbone effects and examines localization measures as functions of system size and contact coupling.

Findings

Transition from diffusive to localized regime in short systems

Localization length and participation number become size-independent in the thermodynamic limit

Discrepancies in experimental results may originate from length-dependent effects

Abstract

In this work we investigate the electronic transport along model DNA molecules using an effective tight-binding approach that includes the backbone on site energies. The localization length and participation number are examined as a function of system size, energy dependence, and the contact coupling between the leads and the DNA molecule. On one hand, the transition from an diffusive regime to a localized regime for short systems is identified, suggesting the necessity of a further length scale revealing the system borders sensibility. On the other hand, we show that the lenght localization and participation number, do not depended of system size and contact coupling in the thermodynamic limit. Finally we discuss possible length dependent origins for the large discrepancies among experimental results for the electronic transport in DNA sample.