Grzegorz Gorski, Jerzy Mizia
We propose a new way of analyzing the Hubbard model using equations of motion (EOM) for the higher-order Green's functions approach within rhe DMFT scheme. The EOM method is combined together with Edwards-Hertz interpolating approximation and the second order perturbation theory (SOPT). Such EOM approach describes well not only the strong-coupling but also the weak-coupling results, where the three center density of states (DOS) structure with two Hubbard bands and the quasiparticle resonance peak is obtained. At small Coulomb interactions and zero temperature the height of the quasiparticle resonance peak on the Fermi energy is constant similarly as in the full DMFT method with numerical (Quantum Monte Carlo) or with analytical (e.g. iterative perturbation theory) calculations.
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http://arxiv.org/abs/1211.6038
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