Note: Depletion potentials in non-additive asymmetric binary mixtures of hard-spheres

摘要

During the last few decades, intense research efforts have been directed to understand the relationship between the effective interaction among particles, u~(eff)(r), and the morphology and phase behavior of a large diversity of materials.~1 Effective potentials represent a reduced description of many-body systems, since the explicit incorporation of all the degrees of freedom in any theoretical framework is an impossible task. Based on the contraction of the description, developed within the framework of integral equations theory, we have recently shown that the depletion potential among big particles, u_(11)~(eff)(r), in an additive asymmetric binary mixture of hard-spheres can be calculated at all particle concentrations.~1 In fact, it is possible to evaluate the effective potential near the theoretically predicted demixing transition provided the difference between the effective and bare bridge functions of the observable species (in this case the big spheres) is explicitly known. There is not established universal bridge function for additive binary mixtures of hard-spheres. However, we have demonstrated that for this type of systems a variant of the Verlet closure, proposed by Kinoshita,~2 allowed us to accurately determine all the structural functions needed to evaluate the effective pair potential between big spheres.~1