Structure and dynamics of liquid water between plates

Abstract

Using the recently developed SPC-FP water model (simple point charge model with flexible bonds and polarization) and the molecular dynamics method, we investigate the structure and properties of liquid water between two rigid plates. In one case the plates are neutral and in the other the plates are electrically charged. In both cases substantial differences from bulk state water are found, structurally and dynamically. We observe some anomalies compared with normal liquids and attribute these to the breakage of hydrogen bonds under the influence of the solid–liquid interface. Adding an external torque enhances such breakage through the attempted alignment of the water molecules. A combination of these two contributions determines the resultant dynamical behavior of water between charged plates. The information obtained from this work should be helpful in the understanding of ‘‘hydrophobic effects’’ in aqueous solutions. The behavior of water near large polar or nonpolar molecular solutes is also revealed by these studies.