Relationships Among Liquid–Vapor IInterfacial Region Properties: Predictions of a Thermodynamic Model

In theoretical models and molecular dynamics simulations of the iInterfacial region between a liquid and vapor phase, three properties are usually of primary iInterest: the iInterfacial tension, the iInterfacial region thickness, and the density gradient in the iInterfacial region. While these properties can be determined from molecular dynamics simulations by collecting appropriate statistics, such results do not explicitly provide an indication of the iInterrelationship among these characteristics. This paper presents theoretical predictions of the relationships among iInterfacial tension, the iInterfacial region thickness, and the density gradient in the iInterfacial region that are derived from a theoretical model of the thermodynamic properties of the iInterfacial region. Explicit relations among iInterfacial region properties are obtained from a modified version of the classical mean field model that incorporates Redlich-Kwong fluid properties. Comparisons are preseInted that indicate that the theoretical relations among the iInterfacial region properties are consistent with trends indicated by experimental data. Use of the theoretical model relations to determine the iInterfacial tension using the mean density profile obtained from a molecular dynamics simulation is also explored. This method is shown to predict values comparable to traditional methods for determining iInterfacial tension in molecular dynamics simulations while requiring significantly less computational effort.