Microcanonical Thermodynamics of First Order Phase Transitions studied in the Potts Model

TL;DR

This paper explores how microcanonical ensemble analysis reveals key features of first order phase transitions in the Potts model, including phase coexistence and negative specific heat, which are less apparent in canonical approaches.

Contribution

It demonstrates the importance of microcanonical configurations in understanding first order phase transitions and characterizes the associated thermodynamic properties.

Findings

Identification of phase coexistence configurations in microcanonical ensemble

Link between backbending in caloric curve and interphase surface entropy

Observation of negative specific heat in finite systems

Abstract

Phase transitions of first and second order can easily be distinguished in small systems in the microcanonical ensemble. Configurations of phase coexistence, which are suppressed in the canonical formulation, carry important information about the main characteristics of first order phase transitions like the transition temperature, the latent heat, and the interphase surface tension. The characterisitc backbending of the micro- canonical caloric equation of state T(E) (not to be confused with the well known Van der Waals loops in ordinary thermodynamics) leading to a negative specific heat is intimatly linked to the interphase surface entropy.