Electron Attachment Induced Shape Resonances in AT Base Pairs

TL;DR

This study explores how base pairing and stacking interactions affect electron attachment shape resonances in AT base pairs, revealing the role of intermolecular interactions in DNA electron processes.

Contribution

It provides the first detailed computational analysis of resonance behavior in AT pairs considering stacking and pairing effects.

Findings

Seven {c}* shape resonances identified for AT geometries.

Resonance delocalization over nucleobases increases in stacked configurations.

Stacking interactions stabilize resonances, extending their lifetimes.

Abstract

In this work, we investigated the influence of base pairing and {\pi}-{\pi} stacking interactions on electron attachment induced shape resonances in the adenine-thymine (AT) base pair. Resonance positions and widths are computed using a DLPNO based equation of motion coupled-cluster approach in conjunction with the Pad\'e analytical continuation method. Seven {\pi}* shape resonances are identified for both linear and stacked AT geometries, consistent with the total number of resonances in isolated adenine and thymine. Natural orbital analysis reveals that low-energy resonances exhibit significant electron density delocalization over both nucleobases. This delocalization is enhanced in the stacked geometry, leading to appreciable stabilization and increased lifetimes of the resonance states. These results highlight the important role of intermolecular interactions in modulating electron attachment processes in DNA.