A noncollinear density functional theory ansatz for the phononic and thermodynamic properties of $\alpha$-Pu

TL;DR

This paper introduces a novel noncollinear magnetic density functional theory approach to accurately model the phononic and thermodynamic properties of alpha-phase plutonium, addressing its complex ground state behavior.

Contribution

The paper presents a new noncollinear magnetic ansatz within density functional theory that improves the description of plutonium's thermodynamic properties.

Findings

Accurately reproduces experimental phonon density of states

Matches experimental heat capacity data

Replicates thermal expansion measurements

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 $\alpha$-Pu. To do this, we build on recent work in the literature by introducing a novel noncollinear magnetic ansatz for $\alpha$-Pu's ground state. The noncollinear ansatz accurately recovers the experimental phonon density of states, heat capacity, and thermal expansion. These new results on $\alpha$-Pu along with recent results on $\delta$-Pu demonstrate the efficacy of noncollinear ansatzes for the description of plutonium.