Nonanalytic Landau functionals shaping the finite-size scaling of fluctuations and response functions in and out of equilibrium

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Auteurs principaux: Ptaszynski, Krzysztof, Esposito, Massimiliano
Format: Preprint
Publié: 2025
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author Ptaszynski, Krzysztof
Esposito, Massimiliano
author_facet Ptaszynski, Krzysztof
Esposito, Massimiliano
contents Landau theory relates phase transitions to the minimization of the Landau functional (e.g., free energy functional), which is expressed as a power series of the order parameter. It has been shown that the critical behavior of certain physical systems can be described using Landau functionals that include nonanalytic terms, corresponding to odd or even noninteger powers of the absolute value of the order parameter. In particular, these nonanalytic terms can determine the order of the phase transition and the values of the critical exponents. Here, we show that such terms can also shape the finite-size scaling behavior of fluctuations of observables (e.g., of energy or magnetization) or the response functions (e.g., heat capacity or magnetic susceptibility) at the continuous phase transition point. We demonstrate this on two examples, the equilibrium molecular zipper and the nonequilibrium version of the Curie--Weiss model.
format Preprint
id arxiv_https___arxiv_org_abs_2502_06226
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Nonanalytic Landau functionals shaping the finite-size scaling of fluctuations and response functions in and out of equilibrium
Ptaszynski, Krzysztof
Esposito, Massimiliano
Statistical Mechanics
Landau theory relates phase transitions to the minimization of the Landau functional (e.g., free energy functional), which is expressed as a power series of the order parameter. It has been shown that the critical behavior of certain physical systems can be described using Landau functionals that include nonanalytic terms, corresponding to odd or even noninteger powers of the absolute value of the order parameter. In particular, these nonanalytic terms can determine the order of the phase transition and the values of the critical exponents. Here, we show that such terms can also shape the finite-size scaling behavior of fluctuations of observables (e.g., of energy or magnetization) or the response functions (e.g., heat capacity or magnetic susceptibility) at the continuous phase transition point. We demonstrate this on two examples, the equilibrium molecular zipper and the nonequilibrium version of the Curie--Weiss model.
title Nonanalytic Landau functionals shaping the finite-size scaling of fluctuations and response functions in and out of equilibrium
topic Statistical Mechanics
url https://arxiv.org/abs/2502.06226