Structural Properties of Small Bosonic Helium Clusters

We use Monte Carlo techniques to investigate the universal behavior of bosonic ⁴He_N clusters with N = 2 to 10 ⁴He atoms.  We determine the energies of these clusters for different realistic He-He potentials.  In addition, we consider a potential energy surface that contains attractive two-body Gaussian interactions and repulsive three-body Gaussian interactions whose parameters are adjusted so as to reproduce the two- and three-body energies of the realistic potentials.  In agreement with earlier work, we find that the energies of the helium clusters depend rather weakly on the underlying potential model.  In addition to the energies, we analyze structural quantities such as the pair distribution function and the radial density.  We quantify the dependence on the underlying potential of these quantities.  To explore the universal behavior of these small quantum droplets further, the two-body scattering length is “artificially” tuned to the unitary point.