Density-functional theory of the solid-liquid interface

A density-functional theory for the structure and surface free energy of solid-liquid interfaces is presented which avoids perturbation and square-gradient approximations by the utilization of (i) the weighted-density approximation for the Helmholtz free-energy functional and (ii) a physical, two-parameter density profile of the interfacial region. The hard-sphere 100 fcc-liquid interface is found to be only 4--5 layers wide with =0. 66kT/^2, consistent with simulations on the similar (r/) ^-12 interface.