Dynamical properties and the proton transfer mechanism in the wetting water layer on Pt(1Â 1Â 1)

We have investigated the structural properties and the dynamics in the (39×39)R16.1° (RT39) wetting layer on Pt(1 1 1) found in recent experiments, by ab initio molecular dynamics simulations. The RT39 bilayer is found to consist of 20% water molecules in the first flat layer, and 66% in the second layer, and a small fraction extending further away. Two-dimensional pair correlation functions are obtained, and calculated vibration spectra are in agreement with experiment. A small fraction of water in this RT39 bilayer dissociates due to both the lateral compression and the substrate effect. Most interestingly, surface mediated proton transfer mechanism in water layers at surface, which differs from the counterparts in bulk water, is discovered.