Global Potential Energy Minima of (H₂O)_n Clusters on Graphite: A Comparative Study of the TIPNP (N=3,4,5) Family

The water-graphite interaction potential proposed recently (Gonz\'alez et al.\emph{J. Phys. Chem. C} \textbf{2007}, \emph{111}, 14862), the three TIP$N$P ($N=3,\:4,\:5$) water-water interaction models, and basin-hopping global optimization are used to find the likely candidates for the global potential energy minima of (H$_{2}$O)$_{n}$ clusters with $n\leq21$ on the (0001)-surface of graphite and to perform a comparative study of these minima. We show that, except for the smaller clusters ($n<6$), for which ab-initio results are available, the three water-water potential models provide mostly inequivalent conformations. While TIP3P seems to favor monolayer water structures for $n<18$, TIP4P and TIP5P favor bilayer or volume structures for $n>6$. These $n$ values determine the threshold of dominance of the hydrophobic nature of the water-graphite interaction at the nanoscopic scale for these potential models.