Quasiparticle energies for large molecules: a tight-binding GW approach

TL;DR

This paper introduces a computationally efficient tight-binding GW method for calculating quasiparticle energies in large molecules, validated against first-principles results and applied to polyacene conformers.

Contribution

The paper develops a minimal-basis tight-binding GW approach that avoids empirical data and accurately predicts quasiparticle energies in large molecular systems.

Findings

Good agreement with first-principles results for benzene and anthracene.

Effective size dependence analysis of quasiparticle gaps in polyacenes.

Method reduces computational complexity for large molecules.

Abstract

We present a tight-binding based GW approach for the calculation of quasiparticle energy levels in confined systems such as molecules. Key quantities in the GW formalism like the microscopic dielectric function or the screened Coulomb interaction are expressed in a minimal basis of spherically averaged atomic orbitals. All necessary integrals are either precalculated or approximated without resorting to empirical data. The method is validated against first principles results for benzene and anthracene, where good agreement is found for levels close to the frontier orbitals. Further, the size dependence of the quasiparticle gap is studied for conformers of the polyacenes ($C_{4n+2}H_{2n+4}$) up to n = 30.