Effects of an electric field on a water bilayer on Ag(111)

Abstract

Based on first-principles calculations, we studied the effects of an electric field on the water bilayer at the water/Ag(111) interface. We find that the commonly accepted ``H-down'' configuration is not the ground state under an external field, but instead, the ``H-down-flipped'' configuration is most stable under a negative $E$ field with the largest spacing between the water and Ag layers, while under a positive $E$ field, the ``H-up'' configuration is most stable. This means that water molecules on Ag(111) are reoriented under an applied $E$ field. The lowest-energy configurations are those that optimize the interaction between the water dipole and the external field, if the hydrogen bonding network of water layer is not disrupted.