Monte Carlo simulation of confined water

Abstract

In living organisms and many applications water is nanoconfined. Here we study water confined between hydrophobic parallel walls as a function of the wall-wall separation Lz between 0.6 and 4.8 nm. We calculate response functions and density by Monte Carlo simulations at different temperatures and pressures of a many-body coarse-grained model of water that has been studied in previous works for the case of a single layer. For all the number of layers considered here we always find that water has density anomaly as in experimental bulk water and that it has a critical phase transition between two liquid phases with different structure, density and energy. We find that the phase diagram changes in a continuous way as the number of layers increases, suggesting that the liquid-liquid critical point should occur also in the bulk case. These results shed light onto the debated bulk-water phase diagram and could be relevant in nanotechnology applications and biological systems