Phase diagram of the ST2 model of water

We evaluate the free energy of the fluid and crystal phases for the ST2 potential 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.