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arXiv · 0812.2456

Efficient perturbation theory for quantum lattice models

H. Hafermann·G. Li·A. N. Rubtsov·M. I. Katsnelson·A. I. Lichtenstein·H. Monien
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Abstract

We present a novel approach to long-range correlations beyond dynamical mean-field theory through a ladder approximation to dual fermions. The new technique is applied to the two-dimensional Hubbard model. We demonstrate that the transformed perturbation series for the nonlocal dual fermions has superior convergence properties over standard diagrammatic techniques. The critical Neel temperature of the mean-field solution is suppressed in the ladder approximation, in accordance with quantum Monte-Carlo (QMC) results. An illustration of how the approach captures and allows to distinguish short- and long-range correlations is given.

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H. Hafermann, G. Li, A. N. Rubtsov, M. I. Katsnelson, A. I. Lichtenstein, H. Monien. 2008-12-12. Efficient perturbation theory for quantum lattice models. https://doi.org/10.1103/physrevlett.102.206401

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