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We derive equations of motion for Green's functions of the multi-orbital Anderson impurity model by differentiating symmetrically with respect to all time arguments. The resulting equations relate the one- and two-particle Green's function…

Strongly Correlated Electrons · Physics 2019-08-14 Josef Kaufmann , Patrik Gunacker , Alexander Kowalski , Giorgio Sangiovanni , Karsten Held

We present a worm sampling method for calculating one- and two-particle Green's functions using continuous-time quantum Monte Carlo simulations in the hybridization expansion (CT-HYB). Instead of measuring Green's functions by removing…

Strongly Correlated Electrons · Physics 2015-10-07 Patrik Gunacker , Markus Wallerberger , Emanuel Gull , Andreas Hausoel , Giorgio Sangiovanni , Karsten Held

We propose efficient measurement procedures for the self-energy and vertex function of the Anderson impurity model within the hybridization expansion continuous-time quantum Monte Carlo algorithm. The method is based on the measurement of…

Strongly Correlated Electrons · Physics 2012-06-01 Hartmut Hafermann , Kelly R. Patton , Philipp Werner

We present a quantum Monte-Carlo algorithm for computing the perturbative expansion in power of the coupling constant $U$ of the out-of-equilibrium Green's functions of interacting Hamiltonians of fermions. The algorithm extends the one…

Strongly Correlated Electrons · Physics 2019-09-23 Corentin Bertrand , Olivier Parcollet , Antoine Maillard , Xavier Waintal

In this paper, we present a new version of the $i$QIST software package, which is capable of solving various quantum impurity models by using the hybridization expansion (or strong coupling expansion) continuous-time quantum Monte Carlo…

Computational Physics · Physics 2017-11-22 Li Huang

We describe an aberration of the resampling estimator for the Green's function customarily used in hybridization expansion continuous-time quantum Monte Carlo. It occurs due to Pauli principle constraints in calculations of Anderson…

Strongly Correlated Electrons · Physics 2022-11-14 Andreas Hausoel , Markus Wallerberger , Josef Kaufmann , Karsten Held , Giorgio Sangiovanni

We extend the continuous-time hybridization expansion solver to a general form, where the hybridization function and retarded interaction are treated on equal footing. Correlation functions can now be directly obtained via functional…

Strongly Correlated Electrons · Physics 2025-04-04 Lei Gu , Jia Luo , Ruqian Wu , Guoping Zhao

We used methods of Bayesian statistical inference and the principle of maximum entropy to analytically continue imaginary-time Green's function generated in quantum Monte Carlo simulations to obtain the real-time Green's functions. For test…

Condensed Matter · Physics 2009-10-28 J. Bonca , J. E. Gubernatis

A novel scheme to solve the quantum eigenvalue problem through the imaginary-time Green function Monte Carlo method is presented. This method is applicable to the excited states as well as to the ground state of a generic system. We…

Nuclear Theory · Physics 2008-11-26 Taksu Cheon

We explore two complementary modifications of the hybridization-expansion continuous-time Monte Carlo method, aiming at large multi-orbital quantum impurity problems. One idea is to compute the imaginary-time propagation using a matrix…

Strongly Correlated Electrons · Physics 2014-07-01 Hiroshi Shinaoka , Michele Dolfi , Matthias Troyer , Philipp Werner

Diffusion Monte Carlo (DMC) simulations for fermions are becoming the standard to provide high quality reference data in systems that are too large to be investigated via quantum chemical approaches. DMC with the fixed-node approximation…

Chemical Physics · Physics 2016-07-06 Andrea Zen , Sandro Sorella , Michael J. Gillan , Angelos Michaelides , Dario Alfè

The main goal of this paper is to define and study new methods for the computation of effective coefficients in the homogenization of divergence-form operators with random coefficients. The methods introduced here are proved to have optimal…

Numerical Analysis · Mathematics 2017-11-01 Jean-Christophe Mourrat

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

In this paper, we present an efficient and stable method to determine the one-particle Green's function in the hybridization-expansion continuous-time (CT-HYB) quantum Monte Carlo method, within the framework of the dynamical mean-field…

Strongly Correlated Electrons · Physics 2012-03-07 Gang Li , Werner Hanke

We perform a comprehensive analysis of the quantum-enhanced Monte Carlo method [Nature, 619, 282-287 (2023)], aimed at identifying the optimal working point of the algorithm. We observe an optimal mixing Hamiltonian strength and analyze the…

Quantum Physics · Physics 2025-07-01 Johannes Christmann , Petr Ivashkov , Mattia Chiurco , Guglielmo Mazzola

Strongly correlated quantum impurity problems appear in a wide variety of contexts ranging from nanoscience and surface physics to material science and the theory of strongly correlated lattice models, where they appear as auxiliary systems…

Strongly Correlated Electrons · Physics 2013-02-19 Hartmut Hafermann , Philipp Werner , Emanuel Gull

A ``forward walking'' Quantum Monte Carlo (QMC) algorithm has been developed to calculate correlation functions for the Hamiltonian lattice formulation of U(1) Yang-Mills theory in (2+1) dimensions. It is shown that Wilson loops can be…

High Energy Physics - Lattice · Physics 2009-10-31 Chris J. Hamer , Robert J. Bursill , Maria Samaras

Numerically exact continuous-time Quantum Monte Carlo algorithm for finite fermionic systems with non-local interactions is proposed. The scheme is particularly applicable for general multi-band time-dependent correlations since it does not…

Strongly Correlated Electrons · Physics 2009-11-10 A. N. Rubtsov , A. I. Lichtenstein

A quantum Monte Carlo method with non-local update scheme is presented. The method is based on a path-integral decomposition and a worm operator which is local in imaginary time. It generates states with a fixed number of particles and…

Statistical Mechanics · Physics 2009-11-11 Kris Van Houcke , Stefan Rombouts , Lode Pollet
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