  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.
