Crystal-melt and melt-vapor interfaces of nickel

The equilibrium crystal-to-melt interfaces for Ni(001) and Ni(111) and the melt-to-vapor interface are investigated at the melting point, with use of molecular-dynamics simulations and the embedded-atom method. The melting temperature of nickel determined from these simulations is 1733±{}22 K, in good agreement with the experimental value. The crystal-to-melt interface is found to be characterized by liquid layering, with properties such as structural order parameters and diffusion coefficients varying gradually across the transition region. The transition region extends over several layers and is more diffuse at the (001) interface. At the melt-to-vapor interface the density increases, driven by an increase in the magnitude of the density-dependent embedding-energy contribution to the cohesive energy of the metal. This behavior is in contrast to that found at the melt-to-vapor interface of nonmetallic systems.