Accuracy of electron densities obtained via Koopmans-compliant hybrid functionals

TL;DR

This paper assesses the accuracy of electron densities and quasiparticle gaps from Koopmans-compliant hybrid functionals by comparing them to exact solutions, highlighting their effectiveness across different systems.

Contribution

It introduces a method to optimize hybrid functionals using physical constraints, demonstrating their high accuracy in predicting electron densities and energy gaps.

Findings

Hybrid functionals produce highly accurate electron densities.

They accurately predict quasiparticle energy gaps.

The screened Fock operator plays a key role in their success.

Abstract

We evaluate the accuracy of electron densities and quasiparticle energy gaps given by hybrid functionals by directly comparing these to the exact quantities obtained from solving the many-electron Schrodinger equation. We determine the admixture of Hartree-Fock exchange to approximate exchange-correlation in our hybrid functional via one of several physically justified constraints, including the generalized Koopmans' theorem. We find that hybrid functionals yield strikingly accurate electron densities and gaps in both exchange-dominated and correlated systems. We also discuss the role of the screened Fock operator in the success of hybrid functionals.