Correlation functions and transport coefficients of metastable fluids

Using the memory function formalism and the complete orthonormal set of hydrodynamical variables, correlation functions of thermodynamic fluctuations of basic variables are investigated. Using the approximation in which one transport mode decays into two hydrodynamical ones in the microscopic variant of the mode-coupling theory, a closed system of integral equations is obtained for the pair correlation functions of thermodynamical fluctuations of basic variables and related relaxation kernels. Behaviour of contributions of hydrodynamical modes into nonlocal frequency-dependent kinetic coefficients is investigated in metastable fluids near the gas–liquid phase transition spinodal. It is shown that the low-frequency behaviour of kinetic coefficients is determined by fluctuations connected with the heat mode and the fluctuations diverge in the neighbourhood of the spinodal line as $(T-T_c)^{-1/8}$.