Symmetry-mediated H2O diffusion on Al{100}

Based upon the full-electron ab initio calculations, we found orientational preferences and correlation for the atop-to-atop motions of an H2O on Al{100}, which originates from the symmetry match between an H2O and the surface square lattice. We have provided theoretical evidence that the favored mechanisms can be classical hopping coupled with either the molecular flipping or in-plane reorientations, with reduced energy barriers compared to those of the simple translational motions; while quantum tunneling assisted motion is not favored for an H2O via the nearest neighbor diffusion.