Hard core bosons on a triangular lattice

The zero temperature phase diagram of an ensemble of hard core bosons on the triangular lattice is studied by means of Green Function Monte Carlo simulations. Results are compared with predictions from a previous theoretical study, based on mean-field and linear spin wave theories. This work yields a considerably more robust superfluid phase (with no crystalline long-range order) than predicted at the mean-field level. Conversely, the domain of existence of the supersolid phase is significantly reduced. The phase diagram includes a first-order transition from a crystal to a superfluid, as well as continuous superfluid-to-supersolid and crystal-to-supersolid transitions.