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The dynamical mean-field theory (DMFT) is a widely applicable approximation scheme for the investigation of correlated quantum many-particle systems on a lattice, e.g., electrons in solids and cold atoms in optical lattices. In particular,…

Strongly Correlated Electrons · Physics 2015-05-30 D. Vollhardt , K. Byczuk , M. Kollar

We introduce regular series expansion for weakly- and moderately-correlated fermionic systems, based on Fluctuating Local Field approach. The method relies on the explicit account of leading fluctuating mode(s) and is therefore suitable for…

Strongly Correlated Electrons · Physics 2024-12-25 Ya. S. Lyakhova , S. D. Semenov , A. I. Lichtenstein , A. N. Rubtsov

In the pursuit of accurate descriptions of strongly correlated quantum many-body systems, dynamical mean-field theory (DMFT) has been an invaluable tool for elucidating the spectral properties and quantum phases of both phenomenological…

Strongly Correlated Electrons · Physics 2019-10-07 Carlos Mejuto-Zaera , Norm M. Tubman , K. Birgitta Whaley

We extend the nonequilibrium dynamical mean field (DMFT) formalism to inhomogeneous systems by adapting the "real-space" DMFT method to Keldysh Green's functions. Solving the coupled impurity problems using strong-coupling perturbation…

Strongly Correlated Electrons · Physics 2014-08-15 Martin Eckstein , Philipp Werner

Dynamical mean-field theory (DMFT) is a non-perturbative technique for the investigation of correlated electron systems. Its combination with the local density approximation (LDA) has recently led to a material-specific computational scheme…

Strongly Correlated Electrons · Physics 2009-11-10 D. Vollhardt , K. Held , G. Keller , R. Bulla , Th. Pruschke , I. A. Nekrasov , V. I. Anisimov

We here present how a self-consistent solution of the dynamical mean field theory equations can be obtained using exact diagonalization of an Anderson impurity model with accuracies comparable to those found using renormalization group or…

Strongly Correlated Electrons · Physics 2014-08-06 Y. Lu , M. Höppner , O. Gunnarsson , M. W. Haverkort

The diagramatic Monte Carlo method has so far been primarily used in connection with the weak coupling expansion. Here we show that the strong coupling expansion offers a significant advantage: it can be efficiently implemented on both the…

Strongly Correlated Electrons · Physics 2023-11-17 Kristjan Haule

A new approach is proposed which encompasses the dynamical mean field theory (DMFT) for strongly correlated electron systems and the self-consistent renormalization (SCR) theory of spin fluctuations. The latter is incorporated into DMFT as…

Strongly Correlated Electrons · Physics 2009-10-31 Tetsuro Saso

We propose a fast impurity solver for the general quantum impurity model based on the perturbation theory around the atomic limit, which can be used in combination with the local density approximation (LDA) and the dynamical mean field…

Strongly Correlated Electrons · Physics 2009-11-10 Xi Dai , Kristjan Haule , Gabriel Kotliar

Quantum impurity solvers are the computational bottleneck of quantum embedding approaches to correlated materials, such as dynamical mean-field theory (DMFT). We show that neural networks trained on synthetic, material-agnostic data learn…

Strongly Correlated Electrons · Physics 2026-03-25 Agnes Valenti , Ina Park , Antoine Georges , Andrew J. Millis , Olivier Parcollet

For reliable and efficient inclusion of electron-electron correlation effects in nanosystems we propose a combined density-functional-theory/nonhomogeneous dynamical-mean-field-theory (DFT + DMFT) approach which employs an approximate…

Strongly Correlated Electrons · Physics 2013-11-14 Alamgir Kabir , Volodymyr Turkowski , Talat S. Rahman

We introduce a numerical algorithm to stochastically sample the dual fermion perturbation series around the dynamical mean field theory, generating all topologies of two-particle interaction vertices. We show results in the weak and strong…

Strongly Correlated Electrons · Physics 2016-07-07 Sergei Iskakov , Andrey E. Antipov , Emanuel Gull

We generalize the dynamical-mean field (DMFT) approximation by including into the DMFT equations some length scale via a momentum dependent ``external'' self-energy S(k). This external self-energy describes non-local dynamical correlations…

Strongly Correlated Electrons · Physics 2009-11-11 M. V. Sadovskii , I. A. Nekrasov , E. Z. Kuchinskii , Th. Pruschke , V. I. Anisimov

The Iterated Perturbation Theory (IPT) equations of the Dynamical Mean Field Theory (DMFT) for the half-filled Hubbard model, are solved on nearly real frequencies at various values of the Hubbard parameters $U$, to investigate the nature…

Strongly Correlated Electrons · Physics 2008-08-05 M. B. Fathi , S. A. Jafari

We generalized the recently introduced new impurity solver based on the diagrammatic expansion around the atomic limit and Quantum Monte Carlo summation of the diagrams. We present generalization to the cluster of impurities, which is at…

Strongly Correlated Electrons · Physics 2009-11-11 Kristjan Haule

We present here two alternative schemes designed to correct the high-frequency truncation errors in the numerical treatment of the Bethe-Salpeter equations. The schemes are applicable to all Bethe-Salpeter calculations with a local…

Strongly Correlated Electrons · Physics 2018-08-02 Agnese Tagliavini , Stefan Hummel , Nils Wentzell , Sabine Andergassen , Alessandro Toschi , Georg Rohringer

The bold diagrammatic Monte Carlo (BDMC) method performs an unbiased sampling of Feynman's diagrammatic series using skeleton diagrams. For lattice models the efficiency of BDMC can be dramatically improved by incorporating dynamic…

Statistical Mechanics · Physics 2015-05-20 L. Pollet , N. V. Prokof'ev , B. V. Svistunov

We apply the Dynamical Mean Field (DMFT) approximation to the real, scalar phi^4 quantum field theory. By comparing to lattice Monte Carlo calculations, perturbation theory and standard mean field theory, we test the quality of the…

High Energy Physics - Lattice · Physics 2013-12-16 Oscar Akerlund , Philippe de Forcrand , Antoine Georges , Philipp Werner

Nonequilibrium dynamical mean-field theory (DMFT) solves correlated lattice models by obtaining their local correlation functions from an effective model consisting of a single impurity in a self-consistently determined bath. The recently…

Strongly Correlated Electrons · Physics 2015-06-22 Karsten Balzer , Zheng Li , Oriol Vendrell , Martin Eckstein

We apply a recently introduced hybridization-flow functional renormalization group scheme for Anderson-like impurity models as an impurity solver in a dynamical mean-field theory (DMFT) approach to lattice Hubbard models. We present how…

Strongly Correlated Electrons · Physics 2013-11-21 Michael Kinza , Carsten Honerkamp