Structure and dynamics at the aluminum solid–liquid interface: An ab initio simulation

Abstract

The interface between the [001] face of crystalline aluminum and the coexisting liquid has been studied in an ab initio molecular dynamics simulation using the orbital-free density functional description of the electronic structure. Direct observation of the equilibrium condition gives a melting temperature in excellent agreement with that obtained from the thermodynamic considerations described in the preceding paper [J. Chem. Phys. 113, 5924 (2000)]. With the resolution which can be achieved, no Friedel-type oscillations in the electron density across the interface can be seen. The atomic density profile shows two or three layers extending into the fluid. The first atomic layer beyond that at which the average atomic density falls to the bulk liquid value shows appreciable in-plane order. Monitoring the instantaneous in-plane “scattering intensity” shows that this layer fluctuates in and out of an ordered state on a time scale of picoseconds. In-plane atomic diffusion is slightly faster than interplane diffusion for these first liquid layers.