Ushcats M. Description of the condensation phenomenon for one-component fluids on the basis of the statistical Gibbs approach

The behavior of single-component fluids with realistic interaction potentials is studied in dense regimes and condensation domain. A new approach to evaluate the partition function has been developed, based on the information on interaction parameters, and equations of states have been obtained that remain applicable beyond the convergence region of the known virial series. Limits on the applicability of the virtual equation of state are established and a general theoretical condition is obtained for the saturation point of fluids. The conditions are established under which the cluster expansion remains applicable in all possible regimes of a fluid: from gaseous to liquid, including the phase transition region. For a lattice gas, the "hole-particle" symmetry is proved and equations of states for dense regimes are established, which are symmetrical to the virial expansions. By using a new numerical integration technique, the information on the virial series is obtained for a number of realistic fluid models.