Theory and equation of state of two-component nonadditive hard-disks: an application in the colloidal regime

We use theoretical and Monte Carlo computer simulations to study thermodynamic and structural properties of a binary mixture of nonadditive hard-disks. The nonadditivity parameter is set to assume negative values so as to favour heterocoordination between the two species. The theoretical approaches include the Rescaled Virial Expansion Equation of State, which is based on the knowledge of the virial coefficients of the mixture, and the Rogers-Young Integral-Equation Theory. The comparison with Monte Carlo data shows that the microscopic theory is able to provide a reliable prediction of both the equation of state and the radial distribution functions of the system. These results are of interest because binary mixtures of colloidal particles adsorbed at the interface exhibit a wide range of self-assembly phenomena, and achieving of a reliable fluid state theory for a simple model of these systems is an essential milestone to be able to understand their nature.