60 research outputs found
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 -Fe
We have obtained the equilibrium volumes, bulk moduli, equations of state of
the ferromagnetic cubic and paramagnetic hexagonal 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 -Fe. Moreover, they enhance the effective mass of the
quasiparticles and reduce their lifetimes across the
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
-Fe are discussed.Comment: 6 pages, 3 figure
An dynamical-mean-field-theory investigation of specific heat and electronic structure of and -plutonium
We have carried out a comparative study of the electronic specific heat and
electronic structure of and -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, , 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 . In the second, , plutonium is viewed as being close
to an configuration, and perturbation theory is carried out around the
(LDA+U) starting point bit below . In the latter case the electronic
specific heat coefficient attains a smaller value in -Pu than
in -Pu, in contradiction to experiment, while in the former case our
calculations reproduce the experimentally observed large increase of
in -Pu as compared to the phase. This enhancement of the
electronic specific heat coefficient in -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 . The densities
of states of and -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 -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 -Pu, Am, and
their selected compounds.Comment: submitted to Europhysics Letter
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