Correlation effects in electronic structure of PuCoGa5

We report on results of the first realistic electronic structure calculations of the Pu-based PuCoGa5 superconductor based on the dynamical mean field theory. We find that dynamical correlations due to the local Coulomb interaction between Pu f-electrons lead to substantial modification of the electronic structure with a narrow peak being formed in vicinity of the Fermi energy, in agreement with the experimental photoemission spectra, and in contrast with the recent calculations within the LDA+U method, where only static electronic correlations have been included. Both Pu and Co contribute in equal footing to the narrow peak on the density of states at the Fermi level, the Co partial density of states being prominently affected by electronic correlations on the Pu sites. The k-resolved spectral density is calculated and the theoretical spectral function resolved extended Van Hove singularity near the Fermi energy. This singularity may lead to enchancement of the magnetic susceptebility and favour d-wave superconductivity

Impact of electronic correlations on the equation of state and transport in ϵ\epsilon-Fe

We have obtained the equilibrium volumes, bulk moduli, equations of state of the ferromagnetic cubic $\alpha$ and paramagnetic hexagonal $\epsilon$ phases of iron in close agreement with experiment using an ab initio dynamical mean-field theory approach. The local dynamical correlations are shown to be crucial for a successful description of the ground-state properties of paramagnetic $\epsilon$-Fe. Moreover, they enhance the effective mass of the quasiparticles and reduce their lifetimes across the $\alpha \to \epsilon$ transition leading to a step-wise increase of the resistivity, as observed in experiment. The calculated magnitude of the jump is significantly underestimated, which points to non-local correlations. The implications of our results for the superconductivity and non-Fermi-liquid behavior of $\epsilon$-Fe are discussed.Comment: 6 pages, 3 figure

An dynamical-mean-field-theory investigation of specific heat and electronic structure of α\alpha and δ\delta-plutonium

We have carried out a comparative study of the electronic specific heat and electronic structure of $\alpha$ and $\delta$-plutonium using dynmical mean field theory (DMFT). We use the perturbative T-matrix and fluctuating exchange (T-matrix FLEX) as a quantum impurity solver. We considered two different physical pictures of plutonoium. In the first, $5{f^5}+$, the perturbative treatment of electronic correlations has been carried out around the non-magnetic (LDA) Hamiltonian, which results in an f occupation around a bit above $n_f = 5$. In the second, $5{f^6}-$, plutonium is viewed as being close to an $5{f^6}$ configuration, and perturbation theory is carried out around the (LDA+U) starting point bit below $n_f = 6$. In the latter case the electronic specific heat coefficient $\gamma$ attains a smaller value in $\gamma$-Pu than in $\alpha$-Pu, in contradiction to experiment, while in the former case our calculations reproduce the experimentally observed large increase of $\gamma$ in $\delta$-Pu as compared to the $\alpha$ phase. This enhancement of the electronic specific heat coefficient in $\delta$-Pu is due to strong electronic correlations present in this phase, which cause a substantial increase of the electronic effective mass, and high density of states at $E_F$. The densities of states of $\alpha$ and $\delta$-plutonium obtained starting from the open-shell configuration are also in good agreement with the experimental photoemission spectra.Comment: 6 pages, 3 figure

Multiplet effects in the electronic structure of δ\delta-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 $\delta$-Pu, Am, and their selected compounds.Comment: submitted to Europhysics Letter