Predicting water’s phase diagram and liquid-state anomalies

Water expands upon freezing, has minima in its volume, heat capacity, and isothermal compressibility with temperature, and shows signs of a first-order phase transition when supercooled. We present an analytical molecular theory that can account for these behaviors. It suggests that local network formation and hydrogen-bonding cooperativity between triplets of neighboring molecules are keys to understanding water’s thermodynamics.