GW correlation effects on plutonium quasiparticle energies: Changes in crystal-field splitting

Abstract

We present results for the electronic structure of plutonium by using a recently developed quasiparticle self-consistent GW method (QSGW). We consider a paramagnetic solution without spin-orbit interaction as a function of volume for the face-centred cubic (fcc) unit cell. We span unit-cell volumes ranging from 10% greater than the equilibrium volume of the δ phase to 90% of the equivalent for the α phase of Pu. The self-consistent GW quasiparticle energies are compared to those obtained within the Local Density Approximation (LDA). The goal of the calculations is to understand systematic trends in the effects of electronic correlations on the quasiparticle energy bands of Pu as a function of the localisation of the f orbitals. We show that correlation effects narrow the f bands in two significantly different ways. Besides the expected narrowing of individual f bands (flatter dispersion), we find that an even more significant effect on the f bands is a decrease in the crystal-field splitting of the different bands.

Keywords:

• plutonium
• electron correlations
• GW approximation
• first-principles electronic structure

Acknowledgements

This work was carried out under the auspices of the National Nuclear Security Administration of the US Department of Energy at Los Alamos National Laboratory under Contract No. DE-AC52-06NA25396. ANC would like to thank Mark van Schilfgaarde and Takao Kotani for informative discussions.