Does hybrid density functional theory predict a non-magnetic ground state for delta-Plutonium?

TL;DR

This study evaluates hybrid density functionals with varying Hartree-Fock exchange fractions to predict the magnetic state of delta-Plutonium, finding that higher HF exchange can induce a non-magnetic ground state but overall performance is comparable to pure DFT.

Contribution

The paper systematically assesses the impact of different HF exchange fractions in hybrid functionals on delta-Plutonium's properties, revealing limitations in their predictive superiority over pure DFT.

Findings

55% HF exchange yields a non-magnetic ground state

Hybrid functionals increase 5f electron localization

Performance comparable to pure DFT for delta-Plutonium

Abstract

Hybrid density functionals, which replaces a fraction of density functional theory (DFT) exchange with exact Hartree-Fock (HF) exchange, have been used to study the structural, magnetic, and electronic properties of delta-Plutonium. The fractions of exact Hartree-Fock exchange used were 25%, 40%, and 55%. Compared to the pure PBE functional, the lattice constants expanded with respect to the experimental value when the PBE-HF hybrid functionals were applied. A non-magnetic ground state was realized for 55% HF contribution; otherwise the ground state was anti-ferromagnetic. The 5f electrons tend to exhibit slight delocalization or itinerancy for the pure PBE functional and well-defined localization for the hybrid functionals, with the degree of 5f electron localization increasing with the amount of HF exchange. Overall, the performance of the hybrid density functionals do not seem superior to pure density functionals for delta-Plutonium.