A DFT based study of the gold-water interface

Abstract

A gold/water interface has been investigated with the DFT-based self-consistentcharge density-functional tight-binding (SCC-DFTB) method using a full cell model with periodic boundary conditions. Born-Oppenheimer molecular-dynamics simulations for water on the surfaces of two Au60 electrode slabs were computed. We have demonstrated the applicability of this method to study the structural and dynamical properties of the gold/water interface in a system with periodic-boundary conditions. The results of the simulation clearly show a dependency on the charged electrodes by means of the orientation of the water molecules and the ensuing polarisation of the cell. However, it was also shown that this polarisating e ect is con ned almost exclusively to rst few angstroms away from the electrode . This is indicative of the rather short-range screening behaviour of water. The present study is a feasibility study of models with periodic-boundary conditions and beckons further analysis of metal/electrolyte interfaces on a dependable atomic scale, using periodic boundary conditions.