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A Monte Carlo sampling of diagrammatic corrections to the non-crossing approximation is shown to provide numerically exact estimates of the long-time dynamics and steady state properties of nonequilibrium quantum impurity models. This…

Strongly Correlated Electrons · Physics 2012-12-21 Emanuel Gull , David R. Reichman , Andrew J. Millis

We employ constrained path Auxiliary Field Quantum Monte Carlo (AFQMC) in the pursuit of studying physical nuclear systems using a lattice formalism. Since AFQMC has been widely used in the study of condensed-matter systems such as the…

Nuclear Theory · Physics 2024-07-16 Ryan Curry , Jayani Dissanayake , Stefano Gandolfi , Alexandros Gezerlis

We applied a mean-field approach associated to Monte Carlo simulations in order to study the spin-1 ferromagnetic Blume-Capel model in the square and the linear lattice. This new technique, which we call MFT-MC, determines the molecular…

Statistical Mechanics · Physics 2016-07-06 J. Roberto Viana , Octavio D. Rodriguez Salmon , Minos A. Neto

We introduce a cluster DMFT (Dynamical Mean Field Theory) approach to study the normal state of the iron pnictides and chalcogenides. In the regime of moderate mass renormalizations, the self-energy is very local, justifying the success of…

Strongly Correlated Electrons · Physics 2017-05-17 Patrick Sémon , Kristjan Haule , Gabriel Kotliar

Determining ground state energies of quantum systems by hybrid classical/quantum methods has emerged as a promising candidate application for near-term quantum computational resources. Short of large-scale fault-tolerant quantum computers,…

Quantum Physics · Physics 2016-10-25 Nicholas C. Rubin

We provide a unified, comprehensive treatment of all operators that contribute to the anti-ferromagnetic, ferromagnetic, and charge-density-wave structure factors and order parameters of the hexagonal Hubbard Model. We use the Hybrid Monte…

Strongly Correlated Electrons · Physics 2021-11-01 Johann Ostmeyer , Evan Berkowitz , Stefan Krieg , Timo A. Lähde , Thomas Luu , Carsten Urbach

Semiconductor artificial graphene nanostructures where Hubbard model parameter $U/t$ can be of the order of 100, provide a highly controllable platform to study strongly correlated quantum many-particle phases. We use accurate variational…

Mesoscale and Nanoscale Physics · Physics 2023-11-01 Gökhan Öztarhan , E. Bulut Kul , Emre Okcu , A. D. Güçlü

We report the results of a Monte Carlo study of a model of (III,Mn)V diluted magnetic semiconductors which uses an impurity band description of carriers coupled to localized Mn spins and is applicable for carrier densities below and around…

Condensed Matter · Physics 2009-11-07 Malcolm P. Kennett , Mona Berciu , R. N. Bhatt

We propose an improved fast multi-orbital impurity solver for the dynamical mean field theory (DMFT) based on equations of motion (EOM) of Green's functions and decoupling scheme. In this scheme the inter-orbital Coulomb interactions are…

Strongly Correlated Electrons · Physics 2015-05-30 Qingguo Feng , P. M. Oppeneer

We examine the quality of the local self-energy approximation, applied here to models of multiple quantum impurities coupled to an electronic bath. The local self-energy is obtained by solving a single-impurity Anderson model in an…

Strongly Correlated Electrons · Physics 2015-10-05 Andrew K. Mitchell , Ralf Bulla

The inchworm expansion is a promising approach to solving strongly correlated quantum impurity models due to its reduction of the sign problem in real and imaginary time. However, inchworm Monte Carlo is computationally expensive,…

Strongly Correlated Electrons · Physics 2024-11-21 Hugo U. R. Strand , Joseph Kleinhenz , Igor Krivenko

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

Quantum Monte Carlo (QMC) is an advanced simulation methodology for studies of manybody quantum systems. In this review, we focus on the electronic structure QMC, i.e., methods relevant for systems described by the electron-ion…

Other Condensed Matter · Physics 2010-08-16 Michal Bajdich , Lubos Mitas

We present the effective action and self-consistency equations for the bosonic dynamical mean field (B-DMFT) approximation to the bosonic Hubbard model and show that it provides remarkably accurate phase diagrams and correlation functions.…

Strongly Correlated Electrons · Physics 2013-05-29 Peter Anders , Emanuel Gull , Lode Pollet , Matthias Troyer , Philipp Werner

Finite temperature auxiliary field-based Quantum Monte Carlo methods, including Determinant Quantum Monte Carlo (DQMC) and Auxiliary Field Quantum Monte Carlo (AFQMC), have historically assumed pivotal roles in the investigation of the…

Quantum Physics · Physics 2021-02-03 Tong Shen , Yuan Liu , Yang Yu , Brenda Rubenstein

The Dynamical Mean-Field theory (DMFT) approach to the Hubbard model requires a method to solve the problem of a quantum impurity in a bath of non-interacting electrons. Iterated Perturbation Theory (IPT) has proven its effectiveness as a…

Strongly Correlated Electrons · Physics 2013-05-30 Louis-Francois Arsenault , Patrick Semon , A. -M. S. Tremblay

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

Due to the intrinsic complexity of the quantum many-body problem, quantum Monte Carlo algorithms and their corresponding Monte Carlo configurations can be defined in various ways. Configurations corresponding to few Feynman diagrams often…

Strongly Correlated Electrons · Physics 2019-04-30 Alexander Kowalski , Andreas Hausoel , Markus Wallerberger , Patrik Gunacker , Giorgio Sangiovanni

A new algorithm for analytic continuation of noisy quantum Monte Carlo (QMC) data from the Matsubara domain to real frequencies is proposed. Unlike the widely used maximum-entropy (MaxEnt) procedure, our method is linear with respect to…

Strongly Correlated Electrons · Physics 2011-06-29 I. S. Krivenko , A. N. Rubtsov

We present real-time inchworm quantum Monte Carlo results for single-site dynamical mean field theory on an infinite coordination number Bethe lattice. Our numerically exact results are obtained on the L-shaped Keldysh contour and, being…

Strongly Correlated Electrons · Physics 2017-10-18 Qiaoyuan Dong , Igor Krivenko , Joseph Kleinhenz , Andrey E. Antipov , Guy Cohen , Emanuel Gull