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Impurity solvers play an essential role in the numerical investigation of strongly correlated electrons systems within the "dynamical mean field" approximation. Recently, a new class of continuous-time solvers has been developed, based on a…

Strongly Correlated Electrons · Physics 2011-11-09 Emanuel Gull , Philipp Werner , Andrew J. Millis , Matthias Troyer

We present a new continuous time solver for quantum impurity models such as those relevant to dynamical mean field theory. It is based on a stochastic sampling of a perturbation expansion in the impurity-bath hybridization parameter.…

Strongly Correlated Electrons · Physics 2009-11-11 Philipp Werner , Armin Comanac , Luca De Medici , Matthias Troyer , Andrew J. Millis

An acceleration of continuous time quantum Monte Carlo (CTQMC) methods is a potentially interesting branch of work as they are matchless as impurity solvers of a density functional theory in combination with a dynamical mean field theory…

Strongly Correlated Electrons · Physics 2019-08-07 Taegeun Song , Hunpyo Lee

We extend a previously proposed rotation and truncation scheme to optimize quantum Anderson impurity calculations with exact diagonalization [PRB 90, 085102 (2014)] to density-matrix renormalization group (DMRG) calculations. The method…

Strongly Correlated Electrons · Physics 2019-10-02 Y. Lu , X. Cao , P. Hansmann , M. W. Haverkort

We present a time-domain iteration scheme for solving the Dynamical Mean-Field Theory (DMFT) self-consistent equations using retarded Green's functions in real time. Unlike conventional DMFT approaches that operate in imaginary time or…

Strongly Correlated Electrons · Physics 2026-01-28 Chakradhar Rangi , Aadi Singh , Ka-Ming Tam

The self-energy method for quantum impurity models expresses the correlation part of the self-energy in terms of the ratio of two Green's functions and allows for a more accurate calculation of equilibrium spectral functions than is…

Strongly Correlated Electrons · Physics 2021-11-24 H. T. M. Nghiem , T. A. Costi

We propose to calculate spectral functions of quantum impurity models using the Time Evolving Block Decimation (TEBD) for Matrix Product States. The resolution of the spectral function is improved by a so-called linear prediction approach.…

Strongly Correlated Electrons · Physics 2015-10-28 Martin Ganahl , Markus Aichhorn , Patrik Thunström , Karsten Held , Hans Gerd Evertz , Frank Verstraete

We introduce a representation of electron operators as a product of a spin-carry ing fermion and of a phase variable dual to the total charge (slave quantum rotor). Based on this representation, a new method is proposed for solving…

Strongly Correlated Electrons · Physics 2009-11-07 Serge Florens , Antoine Georges

We improve a recently developed expansion technique for calculating real frequency spectral functions of any one-dimensional model with short-range interactions, by postprocessing computed Chebyshev moments with linear prediction. This can…

Strongly Correlated Electrons · Physics 2014-08-06 Martin Ganahl , Patrik Thunström , Frank Verstraete , Karsten Held , Hans Gerd Evertz

We introduce a method to obtain the specific heat of quantum impurity models via a direct calculation of the impurity internal energy requiring only the evaluation of local quantities within a single numerical renormalization group (NRG)…

Strongly Correlated Electrons · Physics 2012-08-29 L. Merker , T. A. Costi

Quantitative descriptions of strongly correlated materials pose a considerable challenge in condensed matter physics and chemistry. A promising approach to address this problem is quantum embedding methods. In particular, the dynamical…

Quantum Physics · Physics 2024-05-07 Rihito Sakurai , Wataru Mizukami , Hiroshi Shinaoka

We present an algorithm for solving the self-consistency equations of the dynamical mean-field theory (DMFT) with high precision and efficiency at low temperatures. In each DMFT iteration, the impurity problem is mapped to an auxiliary…

Strongly Correlated Electrons · Physics 2013-06-11 D. Rost , F. Assaad , N. Blümer

We extend the recently developed real-time Diagrammatic Monte Carlo method, in its hybridization expansion formulation, to the full Kadanoff-Baym-Keldysh contour. This allows us to study real-time dynamics in correlated impurity models…

Strongly Correlated Electrons · Physics 2015-05-14 Marco Schiró

In this paper a fast impurity solver is proposed for dynamical mean field theory (DMFT) based on a decoupling of the equations of motion for the impurity Greens function. The resulting integral equations are solved efficiently with a method…

Strongly Correlated Electrons · Physics 2009-06-10 Qingguo Feng , Yuzhong Zhang , Harald O. Jeschke

Within the recently introduced auxiliary master equation approach it is possible to address steady state properties of strongly correlated impurity models, small molecules or clusters efficiently and with high accuracy. It is particularly…

Strongly Correlated Electrons · Physics 2015-12-10 Antonius Dorda , Martin Ganahl , Hans Gerd Evertz , Wolfgang von der Linden , Enrico Arrigoni

Quantum embedding theories provide a feasible route for obtaining quantitative descriptions of correlated materials. However, a critical challenge is solving an effective impurity model of correlated orbitals embedded in an electron bath.…

Strongly Correlated Electrons · Physics 2021-01-27 Hiroshi Shinaoka , Yuki Nagai

We present a numerical method for the study of correlated quantum impurity problems out of equilibrium, which is particularly suited to address steady state properties within Dynamical Mean Field Theory. The approach, recently introduced in…

Strongly Correlated Electrons · Physics 2014-04-08 Antonius Dorda , Martin Nuss , Wolfgang von der Linden , Enrico Arrigoni

Recently solvers for the Anderson impurity model (AIM) working directly on the real-frequency axis have gained much interest. A simple and yet frequently used impurity solver is exact diagonalization (ED), which is based on a discretization…

Strongly Correlated Electrons · Physics 2017-10-24 Manuel Zingl , Martin Nuss , Daniel Bauernfeind , Markus Aichhorn

In this work we present and analyze two tensor network-based influence functional approaches for simulating the real-time dynamics of quantum impurity models such as the Anderson model. Via comparison with recent numerically exact…

Strongly Correlated Electrons · Physics 2023-03-15 Nathan Ng , Gunhee Park , Andrew J. Millis , Garnet Kin-Lic Chan , David R. Reichman

We develop a method to study quantum impurity models, small interacting quantum systems linearly coupled to an environment, in presence of an additional Markovian quantum bath, with a generic non-linear coupling to the impurity. We aim at…

Quantum Physics · Physics 2025-03-10 Orazio Scarlatella , Marco Schirò