Water thin film-silica interaction on α-quartz (0001) surfaces

Interactions between thin water films and α-quartz (0001) surfaces are studied using first-principles density functional theory (DFT) calculations. Layer-by-layer water deposition with up to five layers of water film on both bare and fully hydroxylated α-quartz (0001) surfaces is examined. Except for water monolayer adsorption, the interactions between water and bare quartz surfaces with Si-O-Si terminations are found to be relatively weak, with adsorption energies similar to the hydrogen bonding strength. However, the interactions between water and surfaces with hydroxyl terminations are much stronger, with a film-surface bonding energy an order of magnitude larger than on bare surfaces. A stable bilayer configuration is identified on all surfaces. In particular it shields the water-silica interaction effectively and makes a surface inert to water molecules. Examination of lateral translation of water thin films on bare surfaces supports the results of friction experiments.