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Dynamical correlations in multiorbital Hubbard models: fluctuation exchange approximations
V Drchal1, V Janiš, J Kudrnovský
1Institute of Physics, AS CR, Na Slovance 2, CZ-182 21 Praha 8, Czech Republic.
Abstract:
We study the two-band degenerate Hubbard model using the fluctuation exchange approximation (FLEX) and compare the results with quantum Monte Carlo (QMC) calculations. Both the self-consistent and the non-self-consistent versions of the FLEX scheme are investigated. We find that, unlike in the one-band case, in the multiband case, good agreement with the quantum Monte Carlo results is obtained within the electron-electron T-matrix approximation using the full renormalization of the one-particle propagators. The crossover to strong coupling and the formation of satellites is more clearly visible in the non-self-consistent scheme. Finally we discuss the behaviour of the FLEX for higher orbital degeneracy.
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