Fig. 4. Relaxed configurations of the water molecule on the Au surface for different bias voltages (+1.5 V → +, 0 V, and –1.5 V → –), the corresponding angles, and the estimated dipole moment (details in ESI†). The angle α is the angle between the molecular plane and the surface plane, θ is the angle between the isolated molecule dipole and the surface normal, and γ is the angle between the isolated molecule dipole and that calculated from the charge density of the combined Au + H₂O system.