Computer simulation study of a water film in a narrow unwetted slit

Thin films of TIP4P water, confined between two ideal hard walls, have been simulated by the grand canonical Monte Carlo and molecular dynamics methods. Several water film properties, such as function of the slit width (equal to 2, 2.5, 3, and 6 molecular diameters, respectively), have been studied. On the basis of two isotherms at 300 and 600 K, the chemical potential of two-phase coexistence was found, thereby allowing an estimate of the Laplace and disjoining pressures in the capillaries, indicating a strong hydrophobic interaction involving the two walls. The values of the average isothermal compressibility of films are somewhat higher than those for a corresponding bulk liquid. Local characteristics, such as the density and the orientational distribution functions, the components of the pressure tenser, the electric field and electric potential, as well as the self-diffusion coefficients along the slit were calculated for all the studied systems.