Unraveling the dynamic slowdown in supercooled water: The role of dynamic disorder in jump motions
arXiv:2405.08250 · doi:10.1063/5.0209713
Abstract
When a liquid is rapidly cooled below its melting point without inducing crystallization, its dynamics slow down significantly without noticeable structural changes. Elucidating the origin of this slowdown has been a long-standing challenge. Here, we report a theoretical investigation into the mechanism of the dynamic slowdown in supercooled water, a ubiquitous yet extraordinary substance characterized by various anomalous properties arising from local density fluctuations. Using molecular dynamics simulations, we found that the jump dynamics, which are elementary structural change processes, deviate from Poisson statistics with decreasing temperature. This deviation is attributed to slow variables competing with the jump motions, i.e., dynamic disorder. The present analysis of the dynamic disorder showed that the primary slow variable is the displacement of the fourth nearest oxygen atom of a jumping molecule, which occurs in an environment created by the fluctuations of molecules outside the first hydration shell. As the temperature decreases, the jump dynamics become slow and intermittent. These intermittent dynamics are attributed to the prolonged trapping of jumping molecules within extended and stable low-density domains. As the temperature continues to decrease, the number of slow variables increases due to the increased cooperative motions. Consequently, the jump dynamics proceed in a higher-dimensional space consisting of multiple slow variables, becoming slower and more intermittent. It is then conceivable that with further decreasing temperature, the slowing and intermittency of the jump dynamics intensify, eventually culminating in a glass transition.
References in corpus (12)
- Theoretical perspective on the glass transition and amorphous materials
- Irreversible reorganization in a supercooled liquid originates from localised soft modes
- Identifying structural flow defects in disordered solids using machine learning methods
- Excess entropy, Diffusivity and Structural Order in liquids with water-like anomalies
- Anomalies in water as obtained from computer simulations of the TIP4P/2005 model: density maxima, and density, isothermal compressibility and heat capacity minima
- The building blocks of dynamical heterogeneities in dense granular media
- Relationship between Structure, Entropy and Diffusivity in Water and Water-like Liquids
- Averaging local structure to predict the dynamic propensity in supercooled liquids
- BOTAN: BOnd TArgeting Network for prediction of slow glassy dynamics by machine learning relative motion
- Frequency dependence of specific heat in supercooled liquid water and emergence of correlated dynamics
- Diffusion dynamics of supercooled water modeled with the cage-jump motion and hydrogen-bond rearrangement
- Manifestations of the structural origin of supercooled water's anomalies in the heterogeneous relaxation on the potential energy landscape