First-principles photoemission spectroscopy of DNA and RNA nucleobases from Koopmans-compliant functionals

TL;DR

This study uses Koopmans-compliant functionals to accurately predict the spectral and structural properties of DNA and RNA nucleobases, achieving excellent agreement with experimental photoemission data and improving upon traditional density functional theory methods.

Contribution

The paper demonstrates the effectiveness of Koopmans-compliant functionals in accurately predicting spectral and structural properties of nucleobases, advancing first-principles computational techniques.

Findings

Ionization potentials and electron affinities predicted with <0.1 eV error

Photoemission spectra closely match experimental data

Improved structural descriptions over traditional DFT methods

Abstract

The need to interpret ultraviolet photoemission data strongly motivates the refinement of first-principles techniques able to accurately predict spectral properties. In this work we employ Koopmans-compliant functionals, constructed to enforce piecewise linearity in approximate density functionals, to calculate the structural and electronic properties of DNA and RNA nucleobases. Our results show that not only ionization potentials and electron affinities are accurately predicted with mean absolute errors < 0.1 eV, but also that calculated photoemission spectra are in excellent agreement with experimental ultraviolet photoemission spectra. In particular, the role and contribution of different tautomers to the photoemission spectra are highlighted and discussed in detail. The structural properties of nucleobases are also investigated, showing an improved description with respect to local and semilocal density-functional theory. Methodologically, our results further consolidate the role of Koopmans-compliant functionals in providing, through orbital-density-dependent potentials, accurate electronic and spectral properties.