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 T-c2=188 K, rho(c2)=1100 kg.m(-3), P-c2=230 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 P=0.1-190 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 Kless than or equal toTless than or equal to300 K. The CR EOS also allows calculation of the physical limit of stability in supercooled water-the kinetic spinodal, T-KS. At all pressures P<190 MPa, the kinetic spinodal calculated with the CR EOS lies below the homogeneous nucleation temperature, T-H, thus satisfying a physically obvious condition T(KS)less than or equal toT(H). 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. (C) 2002 American Institute of Physics.