Molecular dynamics calculation of the liquid structure up to a solid surface

The technique of molecular dynamics is used to calculate the properties of a liquid phase in contact with a fcc crystal phase. A system of 1680 particles which interact through a Lennard-Jones potential is divided into two closed subsystems by imposing artificial boundaries across which the particles can interact, but not pass. One of the subsystems is melted and a state corresponding to coexisting liquid–solid bulk states is obtained. The constraint is removed and it is observed that the state is maintained, which suggests that the system is in thermodynamic equilibrium. The interface shows a gradual decline of order, and the structure in the middle of the fluid system cannot be distinguished from that of a pure liquid with the same temperature and density. The density profile is also calculated for a fluid up to a solid surface without lattice structure where the layering in the interface is seen to be more pronounced.