Beyond extended dynamical mean-field theory: Dual boson approach to the two-dimensional extended Hubbard model
Abstract
The dual boson approach [Ann. Phys. 327, 1320 (2012)] provides a means to construct a diagrammatic expansion around the extended dynamical mean-field theory (EDMFT). In this paper, we present the numerical implementation of the approach and apply it to the extended Hubbard model with nearest-neighbor interaction . We calculate the EDMFT phase diagram and study the effect of diagrams beyond EDMFT on the transition to the charge-ordered phase. Including diagrammatic corrections to the EDMFT polarization shifts the EDMFT phase boundary to lower values of . The approach interpolates between the random phase approximation in the weak coupling limit and EDMFT for strong coupling. Neglecting vertex corrections leads to results reminiscent of the EDMFT+ approximation. We however find significant deviations from the dual boson results already for small values of the interaction, emphasizing the crucial importance of fermion-boson vertex corrections.
Keywords
Cite
@article{arxiv.1408.2150,
title = {Beyond extended dynamical mean-field theory: Dual boson approach to the two-dimensional extended Hubbard model},
author = {Erik G. C. P. van Loon and Alexander I. Lichtenstein and Mikhail I. Katsnelson and Olivier Parcollet and Hartmut Hafermann},
journal= {arXiv preprint arXiv:1408.2150},
year = {2014}
}
Comments
Published version; 24 pages, 32 figures