Exploring the universal nucleation behaviour and anomalies in sheared supercooled liquids

One of the most ubiquitous and technologically important phenomena in nature is the nucleation of homogeneous flowing systems. Homogeneous nucleation is notoriously challenging to study using computational methods, since it is usually a stochastic rare event according to the spatio-temporal resolution of molecular dynamics (MD) simulations. Imposing a constant shear rate, which is a non-equilibrium effect, adds to the complexity of the problem.

We have formulated a modified Classical Nucleation Theory (called shear-CNT), explicitly incorporating the shear rate as a dependent variable. Shear-CNT enables us to examine the sheared nucleation behaviour of several systems---water, Lennard-Jones and hard-spheres over a wide range of supercoolings and shear rates inaccessible to brute-force MD. Our results reveal that the variation of the nucleation rate with shear is universal.

We show that water has an anomalous non-monotonic sheared nucleation temperature dependence, which originates from the violation of the Stokes-Einstein relation. The results suggest that, in general, any system violating the SE relation (including glass-forming liquids, and simple liquids near the glass transition) will exhibit the same anomaly.