Density functional theory in combination with dynamical mean field theory (DMFT) become a promising approach to realistic electronic structure of materials with local correlations. We discuss recent progress in continuous time quantum Monte Carlo solution of an effective multi-orbital quantum-impurity DMFT problem. In order to include non-local corrections to DMFT we formulate the interacting lattice problem in terms of new dual fermion variables, which allowed to include k-dependence of self-energy in the lowest order of renormalized perturbation theory [1]. The calculations of non-local susceptibilities will be discussed [2]. Prospects of such superperturbation approach to real-energy impurity solver will be analyzed[3].
[1]A. N. Rubtsov, M. I. Katsnelson, and A. I. Lichtenstein, Phys. Rev. B 77, 033101 (2008).
[2]S. Brener, H. Hafermann, A. N. Rubtsov, M. I. Katsnelson, and A.I. Lichtenstein, Phys. Rev. B 77, 195105 (2008).
[3]H. Hafermann, C. Jung, S. Brener, M.I. Katsnelson, A.N. Rubtsov, A.I. Lichtenstein, arXiv:0809.1051.
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