Figure 3. Density of cold and supercooled water as a function of temperature and pressure.

Black curves are the predictions of the crossover two-state model. T_M (dark red) indicates the melting temperature and T_H indicates the homogeneous nucleation temperature. The thick blue line is the liquid–liquid equilibrium curve, with the critical point C. The red line is the line of maximum density, and the green line is the line of a constant LDL fraction of about 0.12. Symbols represent experimental data¹²,¹³,⁵². Mishima's data¹³ have been shifted by at most 0.3% to bring them into agreement with data for stable water, as described in Ref. 48.