Molecular dynamics study on the liquid–vapor interfacial profiles

Molecular dynamics simulations are carried out to study the thermodynamic properties in the liquid–vapor coexistent systems with liquid–vapor interfaces. The interactions between the particles are modeled with a truncated Lennard–Jones pair potential. The density profile, the temperature profile and the pressure tensor are obtained at two different bulk temperatures. There exist a sharp peak and a small valley at the thin region outside the liquid–vapor interface in the local kinetic energy distribution across the interface. When the system temperature increases, the magnitude of the peak and the valley decreases. The non-equilibrium molecular kinetic energy distribution located at the thin region outside the liquid–vapor interface confirms that though the liquid and vapor phases are in thermodynamic equilibrium, the interface may not be in thermostatic equilibrium. This kind of molecular kinetic energy distribution may embody the behavior of energy transport between the liquid and the vapor phases.