Ground state phase diagram of Gaussian-Core bosons in two dimensions
  The ground state of a two-dimensional (2D) system of Bose particles of spin zero, interacting via a repulsive Gaussian-Core potential, has been investigated by means of Quantum Monte Carlo simulations. The quantum phase diagram is qualitatively identical to that of 2D Yukawa bosons. While the system is a fluid at all densities for weak coupling, in the strong coupling regime it transitions upon compression from a low density superfluid to a crystal, and then into a reentrant superfluid phase. No evidence of a (supersolid) cluster crystal phase is seen. 
Peter Kroiss, Massimo Boninsegni, Lode Pollet
cond-mat.stat-mech