Electron correlation effects in americium metal under pressure

Evolution of the electronic structure of elemental americium due to the lattice compression is investigated. We make use of a version of the LDA+DMFT method based on the ''exact diagonalization'' of the multi-orbital Anderson impurity Hamiltonian with the full Coulomb interaction matrix and the spin-orbit coupling. Also, we include the charge density self-consistency. We observe only a relatively minor modifications of the electronic structure with compression, which appears to be in accord with the RXES and XANES spectra at the L₃ edge that were recently determined experimentally. Neither these experiments nor our calculations support the earlier theoretical proposal that the f-electron occupation should increase with compression, leading eventually to a mixed-valence (5f⁶ + 5f⁷) behavior.