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Crucial role of fragmented and isolated defects in persistent relaxation of deeply supercooled water

Saito, Shinji and Bagchi, Biman and Ohmine, Iwao (2018) Crucial role of fragmented and isolated defects in persistent relaxation of deeply supercooled water. In: JOURNAL OF CHEMICAL PHYSICS, 149 (12).

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Official URL: http://dx.doi.org/ 10.1063/1.5044458

Abstract

Properties of water have been well elucidated for temperatures above similar to 230 K and yet mysteries remain in the deeply supercooled region. By performing extensive molecular dynamics simulations on this supercooled region, we find that structural and dynamical instabilities are hidden in the experimentally inaccessible region between 235 K and 150 K. We find a hitherto undiscovered fragmentation from 220 K to 190 K, which is the breakup of large clusters consisting of molecules with a locally distorted tetrahedral structure into small pieces with one or two isolated defects. The fragmentation leads to considerable changes in the relaxation dynamics of water. We reveal a crucial role of specific three-coordinated defects in slow but persistent structural relaxation. The presence of relaxation due to these specific defects makes the water glass transition temperature T-g (=136 K) extremely low and explains why the T-g of water is similar to 1/2 of the melting temperature T-m, much lower than the commonly obeyed 2/3 rule of T-g/T-m. Published by AIP Publishing.

Item Type: Journal Article
Additional Information: Copy right for this article belong to AMER INST PHYSICS
Department/Centre: Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Depositing User: Id for Latest eprints
Date Deposited: 16 Oct 2018 14:23
Last Modified: 16 Oct 2018 14:23
URI: http://eprints.iisc.ac.in/id/eprint/60889

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