Density Functional in Liquid Helium: Recent Applications to Droplets and   Surfaces
  We present a new density functional, which is the result of a natural evolution and improvement of previous density functional theories for liquid helium. We focus on the key ingredients of the theory, showing how they determine important predictions concerning inhomogeneous systems. These predictions turn out to be quite accurate even at the level of interatomic distances. We discuss the results for the free surface and droplets. 
Franco Dalfovo, Andrea Lastri, and Sandro Stringari