Figure 2 : The bulk water isothermal compressibility KT(T, P) in the same P, T ranges of the density data illustrated in the Figure 1, the pressures are identified by means of the same symbols16,18,19,23,25,26,27.

From: A singular thermodynamically consistent temperature at the origin of the anomalous behavior of liquid water

Figure 2

A simple data inspection shows: i) two distinct behaviors of the KT dependence, at the different pressures, in the high and low temperature regimes; ii) at all the reported pressures the KT(T) curves present a minimum value located at the same temperature T* ~ 315 K ±5 K; iii) also for KT, like for ρ, it seems that Pcross is at the borderline of two regions; one of very large volume fluctuations (P < Pcross, and T < T*) and a second one where 〈δV2〉 is comparable with that of the liquid in its stable phases.