639 research outputs found
Interpolative Approach for Solving the Anderson Impurity Model
A rational representation for the self--energy is explored to interpolate the
solution of the Anderson impurity model in general orbitally degenerate case.
Several constrains such as the Friedel's sum rule, positions of the Hubbard
bands as well as the value of quasiparticle residue are used to establish the
equations for the coefficients of the interpolation. We employ two fast
techniques, the slave--boson mean--field and the Hubbard I approximations to
determine the functional dependence of the coefficients on doping, degeneracy
and the strength of the interaction. The obtained spectral functions and
self--energies are in good agreement with the results of numerically exact
quantum Monte Carlo method.Comment: 15 pages, 9 figure
Phase diagram, energy scales and nonlocal correlations in the Anderson lattice model
We study the Anderson lattice model with one f-orbital per lattice site as
the simplest model which describes generic features of heavy fermion materials.
The resistivity and magnetic susceptibility results obtained within dynamical
mean field theory (DMFT) for a nearly half-filled conduction band show the
existence of a single energy scale which is similar to the single ion
Kondo temperature . To determine the importance of inter-site
correlations, we have also solved the model within cellular DMFT (CDMFT) with
two sites in a unit cell. The antiferromagnetic region on the phase diagram is
much narrower than in the single-site solution, having a smaller critical
hybridization and N\'eel temperature . At temperatures above
the nonlocal correlations are small, and the DMFT paramagnetic solution is in
this case practically exact, which justifies the ab initio LDA+DMFT approach in
theoretical studies of heavy fermions. Strong inter-site correlations in the
CDMFT solution for , however, indicate that they have to be properly
treated in order to unravel the physical properties near the quantum critical
point.Comment: 10 page
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