  We evaluate the free energy of the fluid and crystal phases for the ST2
potential [F.H. Stillinger and A. Rahman, J. Chem. Phys. 60, 1545 (1974)] with
reaction field corrections for the long-range interactions. We estimate the
phase coexistence boundaries in the temperature-pressure plane, as well as the
gas-liquid critical point and gas-liquid coexistence conditions. Our study
frames the location of the previously identified liquid-liquid critical point
relative to the crystalline phase boundaries, and opens the way for exploring
crystal nucleation in a model where the metastable liquid-liquid critical point
is computationally accessible.
