  Despite widespread discussion, the role of van der Waals dispersion forces in
wetting remains unclear. Here we show that non-local correlations contribute
substantially to the water-metal bond and that this is an important factor in
governing the relative stabilities of wetting layers and 3D bulk ice. Due to
the greater polarizability of the substrate metal atoms, non-local correlations
between water and the metal exceed those between water molecules within ice.
This sheds light on a long-standing problem, wherein common density functional
theory exchange-correlation functionals incorrectly predict that none of the
low temperature experimentally characterized ice-like wetting layers are
thermodynamically stable.
