The Blume-Capel Model as a $ϕ^6$ Field Theory: A Monte Carlo and Flow Model StudyThe Blume-Capel Model as a $ϕ^6$ Field Theory: A Monte Carlo and Flow Model Study

Ejaaz Merali, Ryan Larson, Ehsan Khatami +1 more

We report Monte Carlo simulations of a continuous spin variant of the Blume-Capel model. We compute the phase diagrams in the crystal-field-temperature plane, as a function of the softness of the spins. We show that normalizing flows, a class of generative models capable of direct sampling without autocorrelation, are effective samplers across the phase diagram, including in the first-order transition region and in the vicinity of the tricritical point. Finite-size scaling analyses of flow samples locate the first- and second-order transitions as well as the tricritical point with accuracy comparable to canonical and extended-ensemble Monte Carlo.We report Monte Carlo simulations of a continuous spin variant of the Blume-Capel model. We compute the phase diagrams in the crystal-field-temperature plane, as a function of the softness of the spins. We show that normalizing flows, a class of generative models capable of direct sampling without autocorrelation, are effective samplers across the phase diagram, including in the first-order transition region and in the vicinity of the tricritical point. Finite-size scaling analyses of flow samples locate the first- and second-order transitions as well as the tricritical point with accuracy comparable to canonical and extended-ensemble Monte Carlo.

arXiv:2610.20982Oct 14, 20260 citations

Tricriticality and the Blume-Capel model: A Monte Carlo study within the microcanonical ensemble

Markus Deserno

The microcanonical partition function ${\ensuremath{\Omega}}_{\ensuremath{\alpha},N}(E)$ of a three-dimensional ferromagnetic simple cubic Blume-Capel model is calculated for several coupling ratios $\ensuremath{\alpha}$ close to and on the first-order side of the tricritical point. To this end a single Monte Carlo simulation of a suitably extended partition function for systems of $L\ifmmode\times\else\texttimes\fi{}L\ifmmode\times\else\texttimes\fi{}L$ spins with $L\ensuremath{\in}{8,10,12,14,18}$ was performed. A finite system analog of the latent heat is introduced in order to define a tricritical point in finite systems as well. An empirical scaling of its coordinates to the thermodynamic limit yields ${\ensuremath{\alpha}}^{(t)}=2.84479\ifmmode\pm\else\textpm\fi{}0.00030$ for the tricritical coupling ratio, and ${k}_{B}{T}^{(t)}/J=1.4182\ifmmode\pm\else\textpm\fi{}0.0055$ for the tricritical transition temperature. The results are compared with values obtained on fcc lattices.The microcanonical partition function ${\ensuremath{\Omega}}_{\ensuremath{\alpha},N}(E)$ of a three-dimensional ferromagnetic simple cubic Blume-Capel model is calculated for several coupling ratios $\ensuremath{\alpha}$ close to and on the first-order side of the tricritical point. To this end a single Monte Carlo simulation of a suitably extended partition function for systems of $L\ifmmode\times\else\texttimes\fi{}L\ifmmode\times\else\texttimes\fi{}L$ spins with $L\ensuremath{\in}{8,10,12,14,18}$ was performed. A finite system analog of the latent heat is introduced in order to define a tricritical point in finite systems as well. An empirical scaling of its coordinates to the thermodynamic limit yields ${\ensuremath{\alpha}}^{(t)}=2.84479\ifmmode\pm\else\textpm\fi{}0.00030$ for the tricritical coupling ratio, and ${k}_{B}{T}^{(t)}/J=1.4182\ifmmode\pm\else\textpm\fi{}0.0055$ for the tricritical transition temperature. The results are compared with values obtained on fcc lattices.

Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topicsNov 1, 199775 citations

Monte Carlo simulation of model spin systems

S. Ramasesha

Proceedings of the Indian Academy of Sciences Section C Engineering SciencesMar 1, 19791 citation

Monte Carlo Simulations of Spin Systems

Wolfhard Janke E

Springer eBooksJan 1, 199639 citations

Tricritical universality in a two-dimensional spin fluid

Nigel B. Wilding, P. Nielaba

Monte Carlo simulations are used to investigate the tricritical point properties of a two-dimensional (2D) spin fluid. Measurements of the scaling operator distributions are employed in conjunction with a finite-size scaling analaysis to locate the tricritical point and determine the directions of the relevant scaling fields and their associated tricritical exponents. The scaling operator distributions and exponents are shown to match quantitatively those of the 2D Blume-Capel model, confirming that both models belong to the same universality class. Mean-field calculations of the tricritical point location are also compared with the simulation measurements. \textcopyright{} 1996 The American Physical Society.Monte Carlo simulations are used to investigate the tricritical point properties of a two-dimensional (2D) spin fluid. Measurements of the scaling operator distributions are employed in conjunction with a finite-size scaling analaysis to locate the tricritical point and determine the directions of the relevant scaling fields and their associated tricritical exponents. The scaling operator distributions and exponents are shown to match quantitatively those of the 2D Blume-Capel model, confirming that both models belong to the same universality class. Mean-field calculations of the tricritical point location are also compared with the simulation measurements. \textcopyright{} 1996 The American Physical Society.

arXiv:cond-mat/9510051Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topicsJan 1, 1996109 citations

The Blume-Capel Model as a

ϕ^6

Field Theory: A Monte Carlo and Flow Model Study