Hybrid Density Functional Studies of $\delta $-Pu

Hybrid density functionals, which replaces a fraction of a density functional theory exchange with exact Hartree-Fock (HF) exchange, have been used to study the structural, magnetic, and electronic properties of $\delta $-Pu. 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. For pure PBE and hybrids functionals with HF exchange amounts of 25{\%} and 40{\%}, the ground state structure was anti-ferromagnetic, while for 55{\%} HF contribution the ground state was non-magnetic. 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 5$f$ 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 $ --Pu.