Multiplet effects in the electronic structure of δ - Pu , Am and their compounds

– We propose a straightforward and efficient procedure to perform dynamical mean-field (DMFT) calculations on the top of the static mean-field LDA+U approximation. Starting from self-consistent LDA+U ground state we included multiplet transitions using the Hubbard-I approximation, which yields a very good agreement with experimental photoelectron spectra of δ-Pu, Am, and their selected compounds. Introduction. – Electronic, magnetic and superconducting properties of actinide elements recently attracted significant interest and attention in the condensed matter physics. Most intriguing are the phenomena at the localization threshold of the 5f series, which is crossed between Pu and Am, where the electron-electron correlations play a prominent role [1, 2]. During last few years, electronic structure calculations of Pu and Am based on the conventional band theoretical methods (the local density or generalized gradient expantion approximations LDA/GGA to the density functional theory) could not explain essental experimental data. While, the LDA/GGA band structure calculations predict a local magnetic moment (ordered or disordered) to form on the Pu [3] and Am [4] atoms, none of them were seen in the experiment [5]. Also, the same papers attempted to evaluate the photoemission spectra (PES) and electronic specific heat in Pu and Am making use of single-particle LDA/GGA densities of states (DOS), incorrectly assuming weak electron correlation character of 5f systems at the borderline between the localized, nonbonding, behaviour and the bonding situation of electronic bands. It was shown recently that the around-mean-field (AMF)-LSDA+U correlated band theory gives non-magnetic ground state for Pu [6] and Am [7]. Also, the equilibrium volumes and bulk moduli for δ-Pu and fcc-Am are calculated in a good agreement with experiment. However, there is a clear disagreement between the AMF-LDA+U calculated DOS and PES, questioning the validity of this approximation. The DMFT calculations [8] using the (AMF)-LSDA+U form of interacting Hamiltonian demonstrated that experimental PES and high γ coefficient of the electronic specific heat in δ-Pu and its selected compounds [9, 10] originate from the excitations, and not from the ground state DOS alone. While accounting for dynamical