Molecular dynamics description of a layer of water molecules on a hydrophobic surface

Abstract

Static and dynamic properties of a layer of water molecules on top of a graphite surface are studied by means of molecular dynamics simulations. The water molecules are described by a simple point charge flexible model, and the graphite is taken to be a set of featureless parallel sheets separated 3.4 Å in the z direction. Our results indicate that, even at the lower temperatures considered, the water layer is not flat, with some hydrogen atoms pointing perpendicularly to the surface plane. The O–H stretching frequencies are also different than those of bulk water, appearing a new peak in the simulated spectra at a frequency approximately 200 wave numbers higher than the main peak. This peak is associated with the presence of non-H-bonded molecules.