Interpolative Approach for Solving Quantum Impurity Model Based on the Slave--Boson Mean--Field Approximation

摘要

A rational representation for the self-energy is explored to interpolate thesolution of the Anderson impurity model in general orbitally degenerate case.Several constrains such as the Friedel's sum rule, high--frequency moments andthe value of quasiparticle residue are used to establish the equations for thecoefficients of the interpolation. We test two fast techniques, theslave--boson mean--field and the Hubbard I approximation to determine thecoefficients. The obtained self--energies are compared with the results ofnumerically exact Quantum Monte Carlo method. We find that using theslave--boson mean--field approach we can construct an accurate self--energy forall frequencies via the proposed interpolation procedure.