Homogeneous nucleation in atomic and molecular scale systems is typically a rare event, beyond the spatiotemporal resolution of conventional molecular simulations. In addition, although the nucleation of static systems has been the focus of intense research, hydrodynamic flow can have complex and far-reaching consequences on nucleation. We present an extended Classical Nucleation Theory, explicitly incorporating the shear rate, using which the free energies and nucleation rates can be determined at conditions of metastability inaccessible to brute-force approaches.<br/><br/>Using this framework, we study the nucleation of several different systems – the atomistic TIP4P/2005, TIP4P/Ice models, the coarse-grained mW water model, a Lennard-Jones (LJ) fluid and a hard sphere colloid- over a wide range of metastabilites and shear rates. Our results reveal that the non-monotonic variation of the nucleation rate with shear is universal. The figure shows the universal behaviour of the min-max normalized nucleation rate with the normalized shear rate.<br/><br/>Building on our CNT-based formalism, we also formulated a simplified theory, which performs well for all systems. We use the simplified model to analyse the temperature dependence of the nucleation behaviour of the water models and the LJ fluid. Anomalies in the nucleation behaviour of water were discovered, which originate from the violation of the Stokes-Einstein relation for supercooled liquids. We conclude that transport properties solely determine the temperature dependence of the nucleation behaviour.

Unearthing universality and anomalies in the nucleation behaviour of supercooled liquids

ACS Spring Meeting 2021

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