Fig. 3.

Gibbs free energy for a water monolayer with N = 4×10⁴ water molecules at P = 1.98 GPa and T = 158 K. The two minima, one at high energy and high density, and the other at low energy and low density, respectively the LDL and HDL phases of the system. The projection of G on the E/N − ρ plane shows that there is a linear relation between the accessible energies and densities for the coexisting states at the chosen P and T. The two minima have approximately the same G value, consistent with the coexistence of two phases