The application of the Gibbs equation for stability limit to the description of phase transitions of the second kind. Calculation of critical exponents

Phase transitions of the second kind occur at the limit of stability (spinodal) common to both phases, and this defines the continuous pattern of these transitions. The equation of the limit of stability, formulated by Gibbs, turns out to be the basic input equation of the theory of phase transitions of the second kind. The characteristic property of spinodal states lies, as is demonstrated in this paper, in the quadratic dependence of second variation of internal energy on the temperature difference. Proceeding from this regularity, the method of calculation of critical exponents is developed.