Spin-orbit coupling in the actinide elements: a critical evaluation of theoretical equilibrium volumes

TL;DR

This paper critically evaluates recent claims about actinide properties, demonstrating that previous computational methods agree well and clarifying the impact of methodological choices on calculated volumes and electronic properties.

Contribution

The paper refutes recent claims of errors in actinide calculations, showing that FP-LMTO and FP-LAPW methods agree and emphasizes the importance of volume-dependent muffin-tin radii.

Findings

FP-LMTO and FP-LAPW calculations agree well

Discrepancies are due to muffin-tin radius choices

Alpha-Pu's 5f electrons are not partially delocalized

Abstract

In a recent paper by Jones et al., it is argued, based on FP-LAPW band-structure calculations, that previous calculations of ground-state properties for actinides, using the FP-LMTO method implemented by J. M. Wills, are in error. We demonstrate in this paper that the conclusions of Jones et. al. are unfounded. Calculations using the FP-LMTO method are compared with calculations performed with the FP-LAPW method and, in contradiction to statements by Jones et. al., they agree very well. The limitation of the present implementation of the spin-orbit coupling is discussed, where especially the 6p states pose a difficulty. The observed discrepancy (0-10%) between the FP-LMTO calculations and the recent FP-LAPW calculation of Jones et. al. is shown to be due to the choice of muffin-tin radius in the calculations. We argue that the choice of a constant muffin-tin radius, common for all calculated volumes, is less satisfactory compared to the choice of a muffin-tin radius that scales with the volume, especially when a large volume interval and open packed structures are considered. The conclusion of Jones et al. that alpha-Pu has partially delocalized 5f electrons is argued to be erroneous.