Does hybrid density functional theory predict a non-magnetic ground state for -Pu?R. Atta-Fynn and A. K. Ray
Physics Department, University of Texas at Arlington - Arlington, TX 76019, USA
received 4 August 2008; accepted in final form 11 December 2008; published January 2009
published online 2 February 2009
Hybrid density functionals, which replace 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 -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 hybrid functionals with HF exchanges 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 5f electron localization increasing with the amount of HF exchange. Overall, the performance of the hybrid density functionals does not seem superior to pure density functionals for -Pu.
71.15.-m - Methods of electronic structure calculations.
71.15.Mb - Density functional theory, local density approximation, gradient and other corrections.
71.27.+a - Strongly correlated electron systems; heavy fermions.
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