3,098 research outputs found
Role of electronic correlations in the Fermi surface formation of NaCoO
Band structure of metallic sodium cobaltate NaCoO (=0.33, 0.48,
0.61 0.72) has been investigated by local density approximation+Hubbard
(LDA+) method and within Gutzwiller approximation for the Co-
manifold. Correlation effects being taken into account results in suppression
of the hole pockets at the Fermi surface in agreement with recent
angle-resolved photo-emission spectroscopy (ARPES) experiments. In the
Gutzwiller approximation the bilayer splitting is significantly reduced due to
the correlation effects. The formation of high spin (HS) state in Co -shell
was shown to be very improbable.Comment: 6 pages, 2 figure
Do crossover functions depend on the shape of the interaction profile?
We examine the crossover from classical to non-classical critical behaviour
in two-dimensional systems with a one-component order parameter. Since the
degree of universality of the corresponding crossover functions is still
subject to debate, we try to induce non-universal effects by adding
interactions with a second length scale. Although the crossover functions
clearly depend on the range of the interactions, they turn out to be remarkably
robust against further variation of the interaction profile. In particular, we
find that the earlier observed non-monotonic crossover of the effective
susceptibility exponent occurs for several qualitatively different shapes of
this profile.Comment: 7 pages + 4 PostScript figures. Accepted for publication in
Europhysics Letters. Also available as PDF file at
http://www.cond-mat.physik.uni-mainz.de/~luijten/erikpubs.htm
First-principles Calculations of the Electronic Structure and Spectra of Strongly Correlated Systems: Dynamical Mean-field Theory
A recently developed dynamical mean-field theory in the iterated perturbation
theory approximation was used as a basis for construction of the "first
principles" calculation scheme for investigating electronic structure of
strongly correlated electron systems. This scheme is based on Local Density
Approximation (LDA) in the framework of the Linearized Muffin-Tin-Orbitals
(LMTO) method. The classical example of the doped Mott-insulator
La_{1-x}Sr_xTiO_3 was studied by the new method and the results showed
qualitative improvement in agreement with experimental photoemission spectra.Comment: 11 pages, 3 Postscript figures, LaTeX, submit in Journal of Physics:
Condensed Matte
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