An analysis of water clustering is used to study the quasi-2D percolation
transition of water adsorbed at planar hydrophilic surfaces. Above the critical
temperature of the layering transition (quasi-2D liquid-vapor phase transition
of adsorbed molecules) a percolation transition occurs at some threshold
surface coverage, which increases with increasing temperature. The location of
the percolation line is consistent with the existence of a percolation
transition at the critical point. The percolation threshold at a planar surface
is weakly sensitive to the size of the system when its lateral dimension
increases from 80 to 150 A. The size distribution of the largest water cluster
shows a specific two-peaks structure in a wide range of surface coverage : the
lower- and higher-size peaks represent contributions from non-spanning and
spanning clusters, respectively. The ratio of the average sizes of spanning and
non-spanning largest clusters is about 1.8 for all studied planes. The two-peak
structure becomes more pronounced with decreasing size of the planar surface
and strongly enhances at spherical surfaces.Comment: 17 pages, 11 figure