A NEARLY FREE-ELECTRON MODEL OF THE PAIR POTENTIAL IN MOLTEN COPPER

An effective interionic pair potential in liquid copper at 1393 K was extracted from the neutron-diffraction data using an iterative fitting procedure based on the modified hypernetted-chain approach. The procedure involved extensive molecular-dynamics simulation using a system of 16 384 particles. The potential, constructed within the framework of the nearly-free-electron approximation, is based on the Dagens-Rasolt-Taylor model, and it is repulsive and positive around the first-neighbour distance. The proposed potential when used in molecular-dynamics calculations reproduces, within the limit of experimental accuracy, the structure factor measured by neutron diffraction, including the long-wavelength region of the structure factor and the isothermal compressibility limit, as well as the experimental value of the self-diffusion coefficient. The bridge function of liquid copper derived from the simulation data is compared with a hard-sphere fluid bridge function obtained in the context of the modified hypernetted-chain approximation.