Thermodynamics of stable and metastable equilibria in water in the T-P region

Water is considered as a regular solution of two structural components, the ir local configurations corresponding to the atomic short-range order of th e Ida and hda modifications of amorphous ice. The expression for the Gibbs potential, Delta G(T,P,c), includes four model constants, i.e. the differen ce of the specific volumes, Delta V-0, entropies, Delta S-0, and energies, Delta E-0, of the Ida and hda components as well as the parameter U charact erizing the mixing energy of the components in the binary solution. The con centration c of the hda component is determined from minimizing Delta G wit h respect to c. The T-P phase diagram calculated on the basis of this model agrees quantitatively with the experimental data and qualitatively with th e computer calculations using the method of molecular dynamic simulation (M DS). (C) 1999 Elsevier Science B.V. All rights reserved.