Kinetic boundary of metastable states in superheated and stretched liquids

A physical boundary of metastable states - kinetic spinodal is introduced a s a locus where the mean time of formation of a critical nucleus becomes sh orter than a characteristic time governing the decay of fluctuations to loc al equilibrium. To extend this definition at negative pressures a new therm odynamic relation for the nucleation barrier has been obtained. The kinetic spinodal in this approach is completely determined by the equation of stat e and by the surface tension of the liquids. Starting from the critical poi nt the kinetic spinodal first traces the limit of stability of superheated liquid, then passes through the negative pressures, thus defining the limit of stability for stretched liquid. For a comparison of the results of calc ulations with the experimental data in the superheated and stretched fluids the thermodynamic properties of methane and water in the metastable region are considered. (C) 1999 Elsevier Science B.V. All rights reserved.