2017/12/08 by Sergei Iskakov, Hanna Terletska, Emanuel Gull
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Cluster (spacecraft) #Cluster expansion #Computer science #Convergence (economics) #Dual (grammatical number) #Fermion #Magnetic and transport properties of perovskites and related materials #Momentum (technical analysis) #Physics #Physics of Superconductivity and Magnetism #Position and momentum space #Quantum electrodynamics #Quantum mechanics #Space (punctuation) #Statistical physics #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.97.125114
published as Phys. Rev. B 97, 125114 (2018) · 12 pages, 5 figures
arxiv created 2017/12/08 · openalex publication_date 2018/03/12 · arxiv updated 2018/03/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
Recent years have seen the development of two types of nonlocal extensions to the single-site dynamical mean field theory. On one hand, cluster approximations, such as the dynamical cluster approximation, recover short-range momentum-dependent correlations nonperturbatively. On the other hand, diagrammatic extensions, such as the dual-fermion theory, recover long-ranged corrections perturbatively. The correct treatment of both strong short-ranged and weak long-ranged correlations within the same framework is therefore expected to lead to a quick convergence of results, and offers the potential of obtaining smooth self-energies in nonperturbative regimes of phase space. In this paper, we present an exact cluster dual-fermion method based on an expansion around the dynamical cluster approximation. Unlike previous formulations, our method does not employ a coarse-graining approximation to the interaction, which we show to be the leading source of error at high temperature, and converges to the exact result independently of the size of the underlying cluster. We illustrate the power of the method with results for the second-order cluster dual-fermion approximation to the single-particle self-energies and double occupancies.