An entropic approach to analyze phase transitions in the q = 3 Potts model

TL;DR

This paper uses an entropic approach via the Wang-Landau algorithm to analyze phase transitions in the three-state Potts model with an external field, revealing complex microcanonical entropy behaviors and multiple phase transition types.

Contribution

It introduces a novel entropic analysis of the Potts model under external fields, linking microcanonical entropy features to cluster formation and phase transition nature.

Findings

Microcanonical entropy curve is detachable and relates to cluster formation.

Both first and second-order phase transitions are observed at different temperatures.

External field strength influences the type and occurrence of phase transitions.

Abstract

Boltzmann's microcanonical entropy is the link between statistical physics and thermodynamics, forasmuch as the behavior of any thermodynamic quantity is directly related to the number of microscopic configurations. Accordingly, in this work, we investigate the behavior of the logarithm of the density of states of the three-state Potts model with an external field applied to one of the states using joint entropic simulations based on the Wang-Landau algorithm. Our analysis reveals that the microcanonical entropy curve is detachable, and each resulting path is related to the formation of clusters. Such a description is consistent with the energy-entropy argument related to the inception of a phase transition. When the external field is reversed and strong, the observed phase transition is from an ordered configuration to cluster formations. The behavior of the microcanonical inverse temperature indicates both first and second-order phase transitions occurring at different temperatures for high values of the external field.