One of water's unsolved puzzles is the question of what determines the lowest temperature to which it can be cooled before freezing to ice. The heat capacity and compressibility of liquid water increases anomalously in the supercooled region, apparently following a power law that would diverge at 225 K, just below the experimental temperature of homogeneous nucleation of ice TH. This suggests that there may be a relation between the anomalous thermodynamics of liquid water and the rate at which it crystallizes. We use molecular simulations with an accurate and efficient coarse-grained model to investigate the relationship between structure and anomalies of liquid water and the rate of crystallization of ice Our results indicate that the critical ice nuclei around TH contain about 100 water molecules, and that the crystallization rate reaches a maximum at Tx = 225 K, a few degrees below the experimental TH. Above Tx the crystallization rate is controlled by nucleation and below Tx is controlled by growth of the nuclei; this implies that supercooled liquid water cannot be equilibrated below Tx. We will discuss the implications of this finding, and the effect of nanoconfinement on the crystallization of water.Moore, E.B. & Molinero, V. Structural transformation in supercooled water controls the crystallization rate of ice. Nature 479 , 506�508 (2011).

Structural transformation in supercooled water controls the crystallization rate of ice

244th National Meeting (2012)

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