Regensburg 2025 – scientific programme
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O: Fachverband Oberflächenphysik
O 27: Solid-Liquid Interfaces: Reactions and Electrochemistry I
O 27.3: Talk
Tuesday, March 18, 2025, 11:00–11:15, H4
Quantitative Modeling of the Coordination and Solvation Dynamics of Electrically Charged Solvated Systems via Molecular Dynamics Simulations — •Zhenyu Wang, Mira Todorova, Christoph Freysoldt, and Jörg Neugebauer — Max Planck Institute for Sustainable Materials
Chemical and biological processes in water are influenced by the dynamics of the water solvation shell of ions. Despite progress in understanding ion solvation dynamics, the structural changes in the solvation shell with varying charge states remain underexplored. This study uses atomistic molecular dynamics calculations to investigate the solvation shell of a Na ion, as a prototype model, focusing on changes in water molecule arrangement due to charge variations. Gaussian process regression is used to analyze the reorientation of H2O molecules as the Na-ion charge is changed from negative to positive. Results show significant effects of the ionic charge on the coordination to neighboring water molecules, which form distinct polyhedral structures, such as tetrahedra, triangles, pyramids, and octahedra. These formed patterns can be effectively characterized by using the H2O-H2O distance and H2O-H2O-H2O angle. At the highest positive charge, H2O molecules form an octahedral configuration, transitioning to pyramidal and triangular bipyramidal structures as the charge decreases. At a neutral charge, the solvation shell reveals maximum dispersion, which transitions into a single cluster at negative charges. This study provides valuable insights into ion solvation behavior and significantly enhances the understanding of ion solvation dynamics in aqueous environments.
Keywords: solvation shell; solvation dynamics; electrochemistry; molecular dynamics simulation; Gaussian process regression