Abstract:
Recently, it has been revival of experimental interest to the electronic and spectroscopic solid state properties of heavy actinides [K. Moore, and G. van der Laan, Rev. Mod. Phys. 81, 235 (2009)]. We study the electron correlation effects in the electronic structure and spectra of Pu, Am, Cm, and Bk metals, focusing on comparison between the theory and available experimental results for valence photoelectron spectra (PES) as well as XAS/EELS. This comparison is often taken as important criterion of truthfulness of the electronic structure calculations. We developed a computational procedure, which we refer to as "local density matrix" approximation (LDMA) to Dynamical Mean-Field theory (DMFT) , that combines the Hubbard-I approximation with the full-potential linearized augmented plane wave (FP-LAPW) method, including self-consistency over the charge density. This implementation is all-electron, includes spin-orbit interaction, and makes no shape approximations for the charge density. The actinides are calculated assuming paramagnetic state with fcc-crystal structure at the experimental equilibrium volumes. The calculated valence spectral densities are in good agreement with the experimental PES and previous DMFT results [J. Shim, K. Haule and G. Kotliar, Nature 446, 513 (2007)]. Next, we make comparison with XAS/EELS experiments for branching ratio B and spin-orbit coupling strength w110. The calculated values of B and w110 are in good agreement with the experiment, and close to the atomic intermediate-coupling (IC) values. We estimate the effective local magnetic moments in paramagnetic phase of Pu, Am, Cm, and Bk in a good agreement with experimental data.

This work was supported by GACR grant 202/07/0644, and German-Czech collaboration program (436TSE113/53/0-1, GACR 202/07/J047).