Regensburg 2022 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 40: Brownian Motion and Anomalous Diffusion

DY 40.7: Vortrag

Donnerstag, 8. September 2022, 11:45–12:00, H20

Molecular dynamics simulations of supercooled water in silica pores — •Markus Haneke, Robin Horstmann, and Michael Vogel — TU Darmstadt, Institut für Physik kondensierter Materie, Hochschulstr. 6, 64289, Darmstadt, Germany

Being highly relevant in biology as well as in technology and other areas, water is subject to extensive research. Especially its anomalies pose questions. Commonly, it is argued that the anomalies of water originate in the supercooled state, which is therefore regularly subject to exploration. To suppress freezing in experimental studies, confinements can be employed, where silica pores proved to be very useful.

Molecular dynamic simulations are a valuable tool to take a closer look. They allow analyses with high spatial and temporal resolution while making it easy to extract dynamic and static information. [1]

Here, we perform simulations to analyse the diffusion of water in silica pores. We want to find the influence of the pore on dynamics, as well as of the capping if the water outside of the pore freezes.

Results of our analysis are, that the diffusion inside of the pore is anomalous and slowed down. The systems show to be subdiffusive. Capping not only restricts diffusion but also slows down local relaxation and yields a nearly triangular probability density of propagation distance, contradicting free 1D-diffusion.

[1] R. Horstmann, L. Hecht, S. Kloth, and M. Vogel. "Structural and Dynamical Properties of Liquids in Confinements: A Review of Molecular Dynamics Simulation Studies". In: Langmuir 2022 38 (21), 6506-6522