Heat-Bath and Metropolis Dynamics in Ising-like Models on Directed Regular Random Graphs

Using a single-site mean-field approximation (MFA) and Monte Carlo simulations, we examine Ising-like models on directed regular random graphs. The models are directed-network implementations of the Ising model, Ising model with absorbing states, and majority voter models. When these nonequilibrium...

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Main Authors: Adam Lipowski, António L. Ferreira, Dorota Lipowska
Format: Article
Language:English
Published: MDPI AG 2023-12-01
Series:Entropy
Subjects:
Online Access:https://www.mdpi.com/1099-4300/25/12/1615
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author Adam Lipowski
António L. Ferreira
Dorota Lipowska
author_facet Adam Lipowski
António L. Ferreira
Dorota Lipowska
author_sort Adam Lipowski
collection DOAJ
description Using a single-site mean-field approximation (MFA) and Monte Carlo simulations, we examine Ising-like models on directed regular random graphs. The models are directed-network implementations of the Ising model, Ising model with absorbing states, and majority voter models. When these nonequilibrium models are driven by the heat-bath dynamics, their stationary characteristics, such as magnetization, are correctly reproduced by MFA as confirmed by Monte Carlo simulations. It turns out that MFA reproduces the same result as the generating functional analysis that is expected to provide the exact description of such models. We argue that on directed regular random graphs, the neighbors of a given vertex are typically uncorrelated, and that is why MFA for models with heat-bath dynamics provides their exact description. For models with Metropolis dynamics, certain additional correlations become relevant, and MFA, which neglects these correlations, is less accurate. Models with heat-bath dynamics undergo continuous phase transition, and at the critical point, the power-law time decay of the order parameter exhibits the behavior of the Ising mean-field universality class. Analogous phase transitions for models with Metropolis dynamics are discontinuous.
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spelling doaj.art-f82e94828d7c421cbe727a98afb82a942023-12-22T14:07:22ZengMDPI AGEntropy1099-43002023-12-012512161510.3390/e25121615Heat-Bath and Metropolis Dynamics in Ising-like Models on Directed Regular Random GraphsAdam Lipowski0António L. Ferreira1Dorota Lipowska2Faculty of Physics, Adam Mickiewicz University in Poznań, 61-614 Poznań, PolandDepartamento de Física, I3N, Universidade de Aveiro, 3810-193 Aveiro, PortugalFaculty of Modern Languages and Literatures, Adam Mickiewicz University in Poznań, 61-874 Poznań, PolandUsing a single-site mean-field approximation (MFA) and Monte Carlo simulations, we examine Ising-like models on directed regular random graphs. The models are directed-network implementations of the Ising model, Ising model with absorbing states, and majority voter models. When these nonequilibrium models are driven by the heat-bath dynamics, their stationary characteristics, such as magnetization, are correctly reproduced by MFA as confirmed by Monte Carlo simulations. It turns out that MFA reproduces the same result as the generating functional analysis that is expected to provide the exact description of such models. We argue that on directed regular random graphs, the neighbors of a given vertex are typically uncorrelated, and that is why MFA for models with heat-bath dynamics provides their exact description. For models with Metropolis dynamics, certain additional correlations become relevant, and MFA, which neglects these correlations, is less accurate. Models with heat-bath dynamics undergo continuous phase transition, and at the critical point, the power-law time decay of the order parameter exhibits the behavior of the Ising mean-field universality class. Analogous phase transitions for models with Metropolis dynamics are discontinuous.https://www.mdpi.com/1099-4300/25/12/1615Ising modeldirected random graphsmean-field approximationnonequilibrium systems
spellingShingle Adam Lipowski
António L. Ferreira
Dorota Lipowska
Heat-Bath and Metropolis Dynamics in Ising-like Models on Directed Regular Random Graphs
Entropy
Ising model
directed random graphs
mean-field approximation
nonequilibrium systems
title Heat-Bath and Metropolis Dynamics in Ising-like Models on Directed Regular Random Graphs
title_full Heat-Bath and Metropolis Dynamics in Ising-like Models on Directed Regular Random Graphs
title_fullStr Heat-Bath and Metropolis Dynamics in Ising-like Models on Directed Regular Random Graphs
title_full_unstemmed Heat-Bath and Metropolis Dynamics in Ising-like Models on Directed Regular Random Graphs
title_short Heat-Bath and Metropolis Dynamics in Ising-like Models on Directed Regular Random Graphs
title_sort heat bath and metropolis dynamics in ising like models on directed regular random graphs
topic Ising model
directed random graphs
mean-field approximation
nonequilibrium systems
url https://www.mdpi.com/1099-4300/25/12/1615
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AT antoniolferreira heatbathandmetropolisdynamicsinisinglikemodelsondirectedregularrandomgraphs
AT dorotalipowska heatbathandmetropolisdynamicsinisinglikemodelsondirectedregularrandomgraphs