In Gallo et al., Section 4, we find told that theoretical and experimental results are today modelled by the presence of "two alternative structures" in water, "described as a low-and a high-density liquid". "The anomalies of supercooled water and the possibility of metastable liquid-liquid separation in water can be explained if water is viewed as a mixture of two interconvertible organizations of hydrogen bonds whose ratio is controlled by thermodynamic equilibrium" . The water molecules are consequently organized "into two distinct groups: one corresponding to lowenergy/low entropy ordered configurations and the other to high-energy/high-entropy configurations.