arXiv:1604.07734 · Physical review. B./Physical review. B
From local to nonlocal correlations: The Dual Boson perspective
E. A. Stepanov, A. Huber, Erik G. C. P. van Loon, Alexander I. Lichtenstein, Mikhail I. Katsnelson
Abstract
Extended dynamical mean-field theory (EDMFT) is insufficient to describe nonlocal effects in strongly correlated systems, since corrections to the mean-field solution are generally large. We present an efficient scheme for the construction of diagrammatic extensions of EDMFT that avoids the usual double-counting problem by using an exact change of variables (the Dual Boson formalism) to distinguish the correlations included in the dynamical mean-field solution and those beyond. With a computational efficiency comparable to the $\mathrm{EDMFT}+\mathrm{GW}$ approach, our scheme significantly improves on the charge order transition phase boundary in the extended Hubbard model.