Analytical solution for time integrals in diagrammatic expansions: Application to real-frequency diagrammatic Monte Carlo

Recent years have seen a revived interest in the diagrammatic Monte Carlo (DiagMC) methods for interacting fermions on a lattice. A promising recent development allows one to now circumvent the analytical continuation of dynamic observables in DiagMC calculations within the Matsubara formalism. This...

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Main Authors: J. Vučičević, P. Stipsić, M. Ferrero
Format: Article
Language:English
Published: American Physical Society 2021-04-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/PhysRevResearch.3.023082
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author J. Vučičević
P. Stipsić
M. Ferrero
author_facet J. Vučičević
P. Stipsić
M. Ferrero
author_sort J. Vučičević
collection DOAJ
description Recent years have seen a revived interest in the diagrammatic Monte Carlo (DiagMC) methods for interacting fermions on a lattice. A promising recent development allows one to now circumvent the analytical continuation of dynamic observables in DiagMC calculations within the Matsubara formalism. This is made possible by symbolic algebra algorithms, which can be used to analytically solve the internal Matsubara frequency summations of Feynman diagrams. In this paper, we take a different approach and show that it yields improved results. We present a closed-form analytical solution of imaginary-time integrals that appear in the time-domain formulation of Feynman diagrams. We implement and test a DiagMC algorithm based on this analytical solution and show that it has numerous significant advantages. Most importantly, the algorithm is general enough for any kind of single-time correlation function series, involving any single-particle vertex insertions. Therefore, it readily allows for the use of action-shifted schemes, aimed at improving the convergence properties of the series. By performing a frequency-resolved action-shift tuning, we are able to further improve the method and converge the self-energy in a nontrivial regime, with only 3–4 perturbation orders. Finally, we identify time integrals of the same general form in many commonly used Monte Carlo algorithms and therefore expect a broader usage of our analytical solution.
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spelling doaj.art-36cacea3c3cc4823bc955a87350382ca2024-04-12T17:09:32ZengAmerican Physical SocietyPhysical Review Research2643-15642021-04-013202308210.1103/PhysRevResearch.3.023082Analytical solution for time integrals in diagrammatic expansions: Application to real-frequency diagrammatic Monte CarloJ. VučičevićP. StipsićM. FerreroRecent years have seen a revived interest in the diagrammatic Monte Carlo (DiagMC) methods for interacting fermions on a lattice. A promising recent development allows one to now circumvent the analytical continuation of dynamic observables in DiagMC calculations within the Matsubara formalism. This is made possible by symbolic algebra algorithms, which can be used to analytically solve the internal Matsubara frequency summations of Feynman diagrams. In this paper, we take a different approach and show that it yields improved results. We present a closed-form analytical solution of imaginary-time integrals that appear in the time-domain formulation of Feynman diagrams. We implement and test a DiagMC algorithm based on this analytical solution and show that it has numerous significant advantages. Most importantly, the algorithm is general enough for any kind of single-time correlation function series, involving any single-particle vertex insertions. Therefore, it readily allows for the use of action-shifted schemes, aimed at improving the convergence properties of the series. By performing a frequency-resolved action-shift tuning, we are able to further improve the method and converge the self-energy in a nontrivial regime, with only 3–4 perturbation orders. Finally, we identify time integrals of the same general form in many commonly used Monte Carlo algorithms and therefore expect a broader usage of our analytical solution.http://doi.org/10.1103/PhysRevResearch.3.023082
spellingShingle J. Vučičević
P. Stipsić
M. Ferrero
Analytical solution for time integrals in diagrammatic expansions: Application to real-frequency diagrammatic Monte Carlo
Physical Review Research
title Analytical solution for time integrals in diagrammatic expansions: Application to real-frequency diagrammatic Monte Carlo
title_full Analytical solution for time integrals in diagrammatic expansions: Application to real-frequency diagrammatic Monte Carlo
title_fullStr Analytical solution for time integrals in diagrammatic expansions: Application to real-frequency diagrammatic Monte Carlo
title_full_unstemmed Analytical solution for time integrals in diagrammatic expansions: Application to real-frequency diagrammatic Monte Carlo
title_short Analytical solution for time integrals in diagrammatic expansions: Application to real-frequency diagrammatic Monte Carlo
title_sort analytical solution for time integrals in diagrammatic expansions application to real frequency diagrammatic monte carlo
url http://doi.org/10.1103/PhysRevResearch.3.023082
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AT mferrero analyticalsolutionfortimeintegralsindiagrammaticexpansionsapplicationtorealfrequencydiagrammaticmontecarlo