Abstract
We propose a new microscopic criterion to determine surface wetting: water wets the surface
whenever its overlayer has a larger adsorption energy than three dimensional clusters on the bare or
water-covered substrate. This conceptually intuitive criterion is validated by detailed �rst-principles
calculations of the energetics of layers and clusters of water on di�erent metal surfaces. This criterion
resolves naturally the current discrepancy between theory and experiment on the wetting behavior of
undissociated water on Ru(0001) and Rh surfaces, as well as the hydrophobic nature of Au surfaces.
It is also able to predict the nature of ice growth (layer-by-layer on Rh, Ru; Stranski-Krastanow on
Pt), depending on the chemical reactivity and lattice constant of the surface.
PACS numbers: 68.43.Hn, 61.46.+w, 68.43.Bc, 82.30.Fi