Singularity-free interpretation of the thermodynamics of supercooled water. II. Thermal and volumetric behavior

According to the singularity-free interpretation of the thermodynamics of supercooled water, the isothermal compressibility, isobaric heat capacity, and the magnitude of the thermal expansion coefficient increase sharply upon supercooling, but remain finite. No phase transition or critical point occurs at low temperatures. Instead, there is a pronounced but continuous increase in volume and a corresponding decrease in entropy at low temperatures, the sharpness of which becomes more pronounced the lower the temperature and the higher the pressure. We investigate the behavior of the response functions, equation of state, and entropy of a schematic waterlike model that exhibits singularity-free behavior, and thereby illustrate the simplest thermodynamically consistent interpretation that is in accord with existing experimental evidence on water's low-temperature anomalies. In spite of its simplicity, the model captures many nontrivial aspects of water's thermodynamics semiquantitatively.