A perturbation scheme for a binary liquid mixture of hard cores with attractive tail

A perturbation scheme based on the Leonard—Henderson—Barker approach is used to investigate the thermodynamic properties of mixing of a binary mixture of hard cores with attractive tail. Then the hard sphere diameter can be dependent on temperature, and the role of non-additivity of the potentials can be established for various conditions of mixing. It becomes possible to deduce the behaviour of different thermodynamic functions like the Gibbs energy of mixing, entropy of mixing and concentration fluctuations under extreme conditions of temperature T and pressure P. The impact of T and P in the segregation (or phase separation) and in the compound forming region is discussed in the light of the non-additivity of the potentials and the size ratio.