Groundstate electronic structure of actinide carbides and nitrides

TL;DR

This paper uses a self-interaction corrected local spin-density approach to study the electronic structure and valency configurations of actinide carbides and nitrides, revealing localization trends and their effects on lattice parameters.

Contribution

It provides a detailed analysis of f-electron localization in actinide compounds, highlighting the transition points and electronic configurations with improved theoretical modeling.

Findings

Gradual increase in f-electron localization from U to Cm

Localization transition explains lattice parameter jump from PuN to AmN

Calculated densities of states agree with photoemission data

Abstract

The self-interaction corrected (SIC) local spin-density approximation (LSD) is used to investigate the groundstate valency configuration of the actinide ions in the actinide mono-carbides, AC (A = U, Np, Pu, Am, Cm), and the actinide mono-nitrides, AN. The electronic structure is characterized by a gradually increasing degree of f-electron localization from U to Cm, with the tendency towards localization being slightly stronger in the (more ionic) nitrides compared to the (more covalent) carbides. The itinerant band-picture is found to be adequate for UC and acceptable for UN, whilst a more complex manifold of competing localized and delocalized f-electron configurations underlies the groundstates of NpC, PuC, AmC, NpN, and PuN. The fully localized 5f-electron configuration is realized in CmC (f7), CmN (f7), and AmN (f6). The observed sudden increase in lattice parameter from PuN to AmN is found to be related to the localization transition. The calculated valence electron densities of states are in good agreement with photoemission data.