An explicit expression for the static structure factor for a multi-Yukawa fluid: the one-component case

By using the mean spherical approximation, we obtain an analytical expression for the static structure factor (SSF) for a monodisperse system of particles interacting through a potential given by a hard-sphere contribution and M Yukawa terms. This expression depends on scaling matrix Gamma, which is determined by solving a set of nonlinear equations. Our theoretical results show that using three Yukawa terms in the closure relation greatly improves the accuracy when compared with hypernetted-chain closure and Monte Carlo simulation data, which display a secondary low-k peak in the SSF, due to the formation of an intermediate range order structure governed by a short-range attraction and a long-range repulsion. We discuss the appearance of such a peak in terms of the microstructure order given by the radial distribution function. Following the original proposal made by Waisman (Mol Phys. 1973; 25: 45-48), we give an explicit expression that improves the structural properties of a hard-sphere system.