Transition barrier at a first-order phase transition in the canonical and microcanonical ensemble

TL;DR

This paper compares the transition barriers at first-order phase transitions in canonical and microcanonical ensembles, revealing that barriers are smaller and grow more slowly in the microcanonical ensemble, especially for larger systems.

Contribution

It provides a comparative analysis of transition barriers in different ensembles and explains the physical reasons behind their differences, supported by Monte Carlo simulations.

Findings

Transition barriers scale as expected in both ensembles.

Barriers are significantly smaller in the microcanonical ensemble.

Growth of barriers with system size is weaker in the microcanonical ensemble.

Abstract

We compare the transition barrier that accompanies a first-order phase transition in the canonical and microcanonical ensemble. This is directly encoded in the probability distributions of standard Metropolis Monte Carlo simulations and a proper microcanonical sampling technique. For the example of droplet formation, we find that in both ensembles the transition barrier scales as expected but that the barrier is much smaller in the microcanonical ensemble. In addition its growth with system size is weaker which will enhance this difference for larger systems. We provide an intuitive physical explanation for this observation.