Regensburg 2016 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 33: Ionic Liquids and Water
CPP 33.9: Vortrag
Mittwoch, 9. März 2016, 12:00–12:15, H40
Diffusion of charged species through water in confined environments: electronic structure and nuclear quantum effects — •Mariana Rossi1,2, Michele Ceriotti2, and David Manolopoulos1 — 1University of Oxford, Oxford, UK — 2École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
The diffusion and transport of protons and hydroxide ions through confined wires of water molecules are important processes both in biology (e.g. ion channels for pH regulation) and for technological applications (e.g. fuel cells). However, an atomistic theoretical understanding of the diffusion process from first principles – including the quantum nature of the nuclei – and the influence of the potential energy surface used to model it is still lacking. We treat here proton and hydroxide ions in isolated water wires of different lengths constrained by apolar cylindrical potentials with density functional theory potential energy surfaces. We use machine learning techniques [1] to identify the (often elusive) charged species and calculate diffusion coefficients including nuclear quantum effects, through path integral molecular dynamics techniques [2]. We propose a model to eliminate finite size effects and estimate the diffusion coefficients, finding that nuclear quantum effects play a role depending on the water-water separation in the potential energy surface, and is more accentuated for the hydroxide ions. [1] Gasparotto, Ceriotti, JCP 141, 174110 (2014) [2] Rossi, Ceriotti, Manolopoulos, JCP 140, 234116 (2014)