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Significance statement
In this work the cooling rate dependence of the glass transition temperature for water is predicted from dynamic facilitation theory. The work quantifies how varying protocols create glasses of water with a wide range of stabilities and characterized by different structural correlations. Using microscopic properties that are computed independently, the resulting predictions are free from empirical fitting parameters. The results in this paper clarify a number of experimental observations including the wide range of measured glass transition temperatures and the origin of the crossover in the transport behavior of supercooled water. The equations and procedures elucidated are equally valid for other glass-forming systems and can be used to develop protocols for obtaining amorphous solids with custom properties.
Journal Reference
The Journal of Chemical Physics 140, 214509 (2014). David T. Limmer.
Princeton Center for Theoretical Science, Princeton University, Princeton NJ 08540.
Abstract
Using a general model for the equilibrium dynamics of supercooled liquids, I compute from molecular properties the emergent length and time scales that govern the nonequilibrium relaxation behavior of amorphous ice prepared by rapid cooling. Upon cooling, the liquid water falls out of equilibrium whereby the temperature dependence of its relaxation time is predicted to change from super-Arrhenius to Arrhenius. A consequence of this crossover is that the location of the apparent glass transition temperature depends logarithmically on cooling rate. Accompanying vitrification is the emergence of a dynamical length-scale, the size of which depends on the cooling rate and varies between angstroms and 10s of nanometers. While this protocol dependence clarifies a number of previous experimental observations for amorphous ice, the arguments are general and can be extended to other glass forming liquids.
