MICROSCOPIC THEORY OF THE LIQUID-SOLID INTERFACE OF HE-4

Based on the shadow wave function we have developed the first microsco pic theory of the interface between a quantum liquid and solid. We ove rcome the difficulties present in other variational theories because n o a priori equilibrium positions for the atoms have to be assumed and localization of particles is exclusively due to interparticle correlat ions. We find that the crystalline order parameters vary smoothly over the interface and the interface itself is mobile. We have extended th e previous wort (Phys. Rev. Lett. 72, 2589 (1994)) to the {111} interf ace of a fee crystal of He-4. The interfacial energy is 0.16 K/Angstro m(2), the width of the interface is about 15 Angstrom and the local de nsity has a dip on the liquid side.