11-16U

An approach is proposed for describing the critical behavior of a two-component system near the critical point of stratification. The system of non-interacting particles is used as a reference system. The calculation of the grand partition function is carried out using a set of collective variables. An exact expression is computed for the Jacobian of transition from Cartesian coordinates to the collective variables. The representation of the grand partition function is found in the form of a functional integral over collective variables. The equation of state is obtained for the two-component system in Gaussian approximation.