Ab initio, calculations for a water layer on Ru(0 0 0 1) predict that to preserve O-Ru bonds, a substantial percentage of weaker, O-(HO)-O-... bonds will optimally be broken, even in its ground state. Thus, the axiom that wetting only occurs if water molecules bind more strongly to a surface than to each other is fundamental to understanding this wetting layer's structure. X-ray photoelectron spectra confirm the present prediction of similar to 6.7% broken H-bonds in the wetting layer at 150 K. (c) 2005 Elsevier B.V. All rights reserved.