Molecular dynamics study of water next to electrified Ag(111) surfaces

The aim of this report is to compare the density profiles, orientation, and structure of water near charged and uncharged Ag(111) interfaces obtained using molecular dynamics calculations with those suggested from a recent experiment. In the simulations, water contained between two parallel Ag(111) surfaces with charge densities of 0.0, 8.85, and 26.55 mu C/cm(2) on the left wall and opposite values on the right wall experiences external electric fields of 0.0, 1.0, and 3.0 V/Angstrom. The predicted orientation and density of water for the zero field case is consistent with previous predictions for water near metal surfaces and indicates that water is present in layers and has an orientational structure similar to that of hexagonal ice. For simulations with charged surfaces, there is a reordering of water throughout the simulation cell in response to the polarization of the water dipoles. We show that the spacing between the peaks in the liquid density profiles obtained from our MD calculations matches the results of the experiment but that, contrary to the experimental results, we have not observed a dramatic increase of water density near the charged metal.