PROBING INTERACTION FORCES IN COLLOIDAL FLUIDS THROUGH STATIC STRUCTURAL DATA - THE INVERSE PROBLEM

Determination of the details and the nature of the interaction forces in dense or strongly interacting dispersions has been approached in recent years using radiation scattering experiments and modern theories of liquid-state physics. Fitting the experimental structure factors to calculated ones based on assumed potentials, however, leads to ambiguous results. We present a perturbation-theory-based predictor-corrector method that recovers the interaction potentials from static structure factors with remarkable accuracy. The versatility and accuracy of the method are illustrated using three classes of potentials (one with a harshly repulsive core, one with a soft core, and a DLVO potential with primary and secondary minima) with theoretically generated structure factors. The method leads to analytical, closed-form expressions for the potential in terms of structure factors, is easy to apply, and enhances the usefulness of radiation scattering data. The practical issues relevant to the application of the method to experimental data are also outlined.