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Regensburg 2019 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 62: Glasses and Glass transition (joint session DY/CPP)

DY 62.3: Vortrag

Freitag, 5. April 2019, 10:30–10:45, H19

Glass transition of water-like models in bulk and confinement — •Robin Horstmann and Michael Vogel — TU Darmstadt, Institut für Festkörperphysik, Hochschulstr. 6, 64289, Darmstadt, Germany

Tetrahedral network formers have a special position among glass-forming liquids. Their well defined local prefered structures cause significant structural changes with temperature but often render the transfer of models of supercooled liquids, e.g. density scaling, difficult. We use molecular dynamics simulations to examine two families of water-like molecules, based on the SPC/E and TIP4P/2005 water models, that vary only in their partial charges to systematically alter the strength of the hydrogen-bonds and, hence, the relevance of tetrahedral order.1 The varied inter-molecular interactions spread dynamics over a wide temperature range with the glass transition temperature Tg and the high temperature activation energy E both changing by a factor of five. Additionally, we study water-like systems in neutral confinements and find unchanged tetrahedral structure but slowed molecular dynamics. To describe the glassy slowdown, we assume that the activation free energy can be split into a constant value E and an exponentially growing contribution Ec(T).2 Common ratios of E/Tg and Ec(T)/Tg are found indicating that the high temperature results can be used to rescale the glassy slowdown in bulk and confinement.

[1] R. Horstmann and M. Vogel, J. Chem. Phys. 147, 034505 (2017)

[2] B. Schmidtke et al., Phys. Rev. E 86, 041507 (2012)

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