Static structure factor for a fluid with interaction of hard spheres plus two Yukawa tails

We determine the static structure factor S(k) for a fluid of hard spheres with two-Yukawa interactions through the application of the mean spherical approximation (MSA) to a multi-component system composed of hard-spheres plus double Yukawa interactions (HSDY). This S(k) depends on scaling parameters Γ_n that satisfy a system of nonlinear equations. We report explicit results for a mono-dispersed HSDY fluid and show that the hard-sphere contributions control the main peak of the S(k),while for wave vectors approaching zero, we predict a cluster peak which could be identified with that of recent experimental results of Liu et al. [Y. Liu, W.-R. Chen, S.H. Chen, J. Chem. Phys. 122 (2005) 044507-1].