Density of States Weighted Decoherence Probe Formalism for Charge Transport in DNA

TL;DR

This paper introduces a DOS-weighted decoherence model for charge transport in DNA that self-consistently accounts for energy-dependent scattering, avoiding unphysical broadening and spurious energy levels, thus improving simulation accuracy.

Contribution

The authors develop a novel DOS-weighted decoherence formalism that iteratively updates scattering rates for more accurate charge transport modeling in DNA.

Findings

The model prevents artificial energy levels and excessive DOS broadening.

Energy and spatially dependent scattering rates improve physical realism.

The approach enhances simulation accuracy for weakly coupled molecular systems.

Abstract

Nanoscale molecular systems such as DNA require an atomistic quantum treatment to accurately capture their electrical properties, owing to their small dimensions. A central challenge in modeling transport through these systems is the inclusion of phase-breaking scattering. Decoherence-probe methods enable such modeling for large systems, but existing implementations have limitations. Energy-independent scattering rates tend to overly broaden energy levels, yielding an unphysically large density of states (DOS) within energy gaps. Conversely, energy-dependent models may introduce spurious energy levels and transmission peaks and require additional fitting parameters. To address these issues, we use a DOSweighted decoherence model in which the scattering rate and equivalently, the associated decoherence probe self-energy is proportional to the local DOS. The model iteratively updates the decoherence selfenergy and the DOS until self-consistency is achieved. This approach yields energy and spatially dependent scattering rates that avoid spurious energy levels without the excessive broadening of DOS in energy gaps. We also examine the impact of partitioning schemes that prevent artificial pathways for charge transport and discuss how they can be avoided. Overall, the DOS-weighted model provides an improved and more physically grounded framework for simulating charge transport in DNA and potentially other weakly coupled molecular systems.