title: Dynamical correlations in multiorbital Hubbard models: fluctuation exchange approximations.
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.
authors.affiliation: Institute of Physics, AS CR, Na Slovance 2, CZ-182 21 Praha 8, Czech Republic.
authors.forename: V
authors.initials: V
authors.lastname: Drchal
authors.forename: V
authors.initials: V
authors.lastname: Janiš
authors.forename: J
authors.initials: J
authors.lastname: Kudrnovský
authors.forename: V S
authors.initials: VS
authors.lastname: Oudovenko
authors.forename: X
authors.initials: X
authors.lastname: Dai
authors.forename: K
authors.initials: K
authors.lastname: Haule
authors.forename: G
authors.initials: G
authors.lastname: Kotliar