STRUCTURAL AND DYNAMICAL PROPERTIES OF SUPERFLUID-HELIUM - A DENSITY-FUNCTIONAL APPROACH

We present a density functional for liquid He-4, properly accounting f or the static response function and the phonon-roton dispersion in the uniform liquid. The functional is used to study both structural and d ynamical properties of superfluid helium in various geometries. The eq uilibrium properties of the free surface, droplets, and films at zero temperature are calculated. Our predictions agree closely with the res ults of ab initio Monte Carlo calculations, when available. The introd uction of a phenomenological velocity-dependent interaction, which acc ounts for backflow effects, is discussed. The spectrum of the elementa ry excitations of the free surface and films is studied.