Parametric crossover model and physical limit of stability in supercooled water

The two-critical point ~TCP! scenario for supercooled water was tested against experimental data with the crossover equation of state ~CR EOS! based on the fundamental results of the fluctuation theory of critical phenomena. The CR EOS predicts a second critical point, CP2, in supercooled water with the parameters Tc25188 K, rc251100 kg•m , Pc25230 MPa, and represents the experimental values of the isothermal compressibility in liquid and supercooled water with an average absolute deviation ~AAD! of about 1.7% in the pressure range P50.1– 190 MPa, the liquid densities with an AAD of about 0.1%, and the heat capacity with an AAD of about 1.0% in the temperature range 245 K<T<300 K. The CR EOS also allows calculation of the physical limit of stability in supercooled water—the kinetic spinodal, TKS . At all pressures P,190 MPa, the kinetic spinodal calculated with the CR EOS lies below the homogeneous nucleation temperature, TH , thus satisfying a physically obvious condition TKS<TH . We show that the CP2 is always lying in the region where no thermodynamic state is possible—the ‘‘nonthermodynamic habitat’’ for supercooled water; therefore, we consider our result as a strong argument for the TCP scenario, but with the unphysical—‘‘virtual,’’ rather than real physical, CP2. © 2002 American Institute of Physics. @DOI: 10.1063/1.1453399#