Correlation strength and orbital differentiation across the phase diagram of plutonium metal

TL;DR

This study investigates the electronic correlation and orbital differentiation in various phases of plutonium using advanced theoretical methods, revealing phase-dependent correlation strengths and orbital behaviors.

Contribution

It provides a detailed analysis of site and orbital dependence of electronic correlations in plutonium phases using DFT+DMFT with vertex corrections, highlighting new insights into their electronic structure.

Findings

Pu-5f states are most correlated in δ-Pu

Orbital differentiation between 5f_{5/2} and 5f_{7/2} is observed

Correlation strength correlates with structure and occupancy

Abstract

We compare the trends on the strength of electronic correlations across the different phases of elemental Pu focusing on its site and orbital dependence, using a combination of density functional theory (DFT) and dynamical mean field theory (DMFT) calculations within the vertex corrected one crossing approximation. We find that Pu-5$f$ states are more correlated in $\delta$-Pu, followed by some crystallographic sites in $\alpha$ and $\beta$ phases. In addition, we observe that Pu-5$f_{5/2}$ and Pu-5$f_{7/2}$ orbital differentiation is a general feature of this material, as is site differentiation in the low symmetry phases. The Pu-5$f_{5/2}$ states show Fermi liquid like behavior whereas the Pu-5$f_{7/2}$ states remaining incoherent down to very low temperatures. We correlate the correlation strength in the different phases to their structure and the Pu-5$f$ occupancy of their crystallographic sites.