Benchmarking GNOF against FCI in challenging systems in one, two and three dimensions

TL;DR

This paper evaluates the effectiveness of the global natural orbital functional (GNOF) in accurately describing strong electron correlation across various challenging one, two, and three-dimensional hydrogen systems and Mott insulators.

Contribution

It demonstrates that GNOF reliably handles both weak and strong correlation without tuning or hybridization, outperforming previous functionals.

Findings

GNOF successfully models diverse hydrogen systems.

GNOF accurately captures strong correlation in Mott insulators.

GNOF outperforms previous functionals in balanced treatment.

Abstract

This work assess the reliability of the recently proposed [Phys. Rev. Lett. 127, 233001, 2021] global natural orbital functional (GNOF) in the treatment of the strong electron correlation regime. We first use an H10 benchmark set of four hydrogen model systems of different dimensionalities and distinctive electronic structures: a 1D chain, a 2D ring, a 2D sheet, and a 3D close-packed pyramid. Second, we study two paradigmatic models for strongly correlated Mott insulators, namely a 1D H50 chain and a 4x4x4 3D H cube. We show that GNOF without hybridization to other electronic structure methods and free of tuned parameters succeeds in treating weak and strong correlation in a more balanced way than the functionals that have preceded it.