Thermodynamics of clusterized matter

TL;DR

This paper investigates the thermodynamics of clusterized matter using statistical models and simulations, revealing that the phase transition occurs along a specific density line and is not a critical point, with implications for neutron star matter.

Contribution

It provides a detailed comparison between analytical and simulation results, clarifies the nature of the phase transition, and extends the analysis to neutron star matter using a Wigner-Seitz formalism.

Findings

Transition occurs along the $ ho= ho_0$ line at all temperatures.

The limiting point is not a critical point despite vanishing surface energy.

Phase diagram sensitivity depends on the statistical ensemble used.

Abstract

Thermodynamics of clusterized matter is studied in the framework of statistical models with non-interacting cluster degrees of freedom. At variance with the analytical Fisher model, exact Metropolis simulation results indicate that the transition from homogeneous to clusterized matter lies along the $\rho=\rho_0$ axis at all temperatures and the limiting point of the phase diagram is not a critical point even if the surface energy vanishes at this point. Sensitivity of the inferred phase diagram to the employed statistical framework in the case of finite systems is discussed by considering the grand-canonical and constant-pressure canonical ensembles. A Wigner-Seitz formalism in which the fragment charge is neutralized by an uniform electron distribution allows to build the phase diagram of neutron star matter.