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O: Fachverband Oberflächenphysik

O 39: Metal substrates: Solid-liquid interfaces

O 39.1: Vortrag

Mittwoch, 25. März 2009, 15:00–15:15, SCH A315

First-principles characterization of water structures at the metal-water interface — •Sebastian Schnur and Axel Groß — Institute für Theoretische Chemie, Universität Ulm, D-89069 Ulm, Germany

A molecular level understanding of the structural arrangement of water molecules at a metal-water interface is one of the most important issues in electrochemistry. Despite numerous studies, the exact microscopic structure of water at a metal-water interface is not fully understood and is still subject of debate between state-of-the-art theory and in-situ surface science techniques. On a number of metal surfaces, deposition of water usually leads to well-ordered structures. In particular, ice-like water bilayers with a √3×√3 hexagonal pattern have been investigated most intensively. The crucial question is whether such an ice-like water pattern remains intact even at room temperature or whether it transforms to a liquid-like structure.

We used ab initio molecular dynamics simulations based on density functional theory to study the water bilayer on different closed packed metal surfaces. Vibrational spectra were obtained from the velocity autocorrelation function recorded in the MD simulation to characterize the water structure. Furthermore, we examined details of the metal-water interaction by considering charge density and work function changes to elucidate the nature of the metal-water interaction. Our results contribute to bridge the gap between theory and experiment by giving a direct molecular level explanation for results obtained in finite-temperature in-situ spectroscopy experiments.