A microscopic theory of surface melting is described and applied to Le
nnard-Jones systems. Our approach is based on density functional theor
y with the hard sphere fluid as a reference system. In particular we u
se a weighted density approximation which yields an accurate Lennard-J
ones bulk phase diagram. Within a practically free minimization of the
functional, we find surface melting of a Lennard-Jones crystal for di
fferent surface orientations. Furthermore the hard-sphere crystal-flui
d interface and the hard-sphere crystal at a hard wall are explored wi
th density functional theory. It is found that the crystal-fluid surfa
ce tension of hard spheres is extremely small and that the hard wall p
refers to be covered by a hard-sphere-solid at solid-liquid coexistenc
e.