A noncollinear density functional theory ansatz for the phononic and thermodynamic properties of $\hat{I}\pm$-Pu

Abstract

Plutonium's phase diagram is host to complex structures and interactions that make the description of its ground state properties elusive. Using all-electron density functional theory, we study the thermodynamic properties of $\hat{I}\pm$-Pu. To do this, we build on recent work in the literature by introducing a novel noncollinear magnetic ansatz for $\hat{I}\pm$-Pu's ground state. The noncollinear ansatz accurately recovers the experimental phonon density of states, heat capacity, and thermal expansion. These new results on $\hat{I}\pm$-Pu along with recent results on $\hat{I}´$-Pu demonstrate the efficacy of noncollinear ansatzes for the description of plutonium.