Localization Properties of Electronic States in Polaron Model of poly(dG)-poly(dC) and poly(dA)-poly(dT) DNA polymers

TL;DR

This study numerically analyzes how various structural factors influence the localization of electronic states in DNA polymers, revealing the effects of hydrogen bonds, twist angles, and system size on electron localization.

Contribution

It provides a detailed numerical investigation of localization properties in DNA models with realistic parameters, highlighting the roles of hydrogen-bond fluctuations and helical twist angles.

Findings

Localization length decreases with hydrogen bond fluctuations.

Twist angles significantly affect localization in poly(dG)-poly(dC).

Resonance structures appear in localization length for small systems.

Abstract

We numerically investigate localization properties of electronic states in a static model of poly(dG)-poly(dC) and poly(dA)-poly(dT) DNA polymers with realistic parameters obtained by quantum-chemical calculation. The randomness in the on-site energies caused by the electron-phonon coupling are completely correlated to the off-diagonal parts. In the single electron model, the effect of the hydrogen-bond stretchings, the twist angles between the base pairs and the finite system size effects on the energy dependence of the localization length and on the Lyapunov exponent are given. The localization length is reduced by the influence of the fluctuations in the hydrogen bond stretchings. It is also shown that the helical twist angle affects the localization length in the poly(dG)-poly(dC) DNA polymer more strongly than in the poly(dA)-poly(dT) one. Furthermore, we show resonance structures in the energy dependence of the localization length when the system size is relatively small.