Dynamical mean-field theory of photoemission spectra of actinide compounds

TL;DR

This paper develops a dynamical mean-field theory approach to model photoemission spectra of actinide compounds, capturing atomic multiplet effects and conduction electron interactions to explain spectral features in PuSe and Am.

Contribution

It introduces a combined atomic and band-structure model using exact diagonalization and local-density approximation for actinide compounds.

Findings

PuSe exhibits a Fermi level resonance from mixed valence.

Atomic multiplet features are identified at larger binding energies.

Am shows a dominant f^6 singlet state with significant f^7 admixture.

Abstract

A model of photoemission spectra of actinide compounds is presented. The complete multiplet spectrum of a single ion is calculated by exact diagonalization of the two-body Hamiltonian of the f^n shell. A coupling to auxiliary fermion states models the interaction with a conduction sea. The ensuing self-energy function is combined with a band Hamiltonian of the compound, calculated in the local-density approximation, to produce a solid state Green's function. The theory is applied to PuSe and elemental Am. For PuSe a sharp resonance at the Fermi level arises from mixed valent behavior, while several features at larger binding energies can be identified with quantum numbers of the atomic system. For Am the ground state is dominated by the |f^6;J=0> singlet but the strong coupling to the conduction electrons mixes in a significant amount of f^7 character.