Homogeneous nucleation under shear in a two-dimensional Ising model: cluster growth, coalescence and breakup

TL;DR

This study investigates how shear influences nucleation in a 2D Ising model, revealing a peak in nucleation rate at intermediate shear rates due to competing effects like growth, coalescence, and breakup.

Contribution

It demonstrates the complex interplay of shear effects on nucleation in a simple driven system and showcases the use of Forward Flux Sampling for rare event simulation.

Findings

Nucleation rate peaks at intermediate shear rates

Shear enhances cluster growth and coalescence

Shear also causes cluster breakup

Abstract

We compute rates and pathways for nucleation in a sheared two dimensional Ising model with Metropolis spin flip dynamics, using Forward Flux Sampling (FFS). We find a peak in the nucleation rate at intermediate shear rate. We analyse the origin of this peak using modified shear algorithms and committor analysis. We find that the peak arises from an interplay between three shear-mediated effects: shear-enhanced cluster growth, cluster coalescence and cluster breakup. Our results show that complex nucleation behaviour can be found even in a simple driven model system. This work also demonstrates the use of FFS for simulating rare events, including nucleation, in nonequilibrium systems.