On the structure of suspensions of charged rodlike particles

Abstract

Structural properties of colloidal suspensions of charged rodlike particles are studied by computer simulation and several perturbation theory schemes. As a model for the interaction, we consider a repulsive screened Coulomb potential between two interaction centers on each rod. — MonteCarlo simulations were performed for both the dilute (c<1/L ³) and the semidilute (c>1/L ³) regimes. Results for the pair correlation function, the static structure factor S ^M(k) and the angular correlation of rod axes were obtained. It turns out that the concentration dependence of the peak position of S ^M(k) shows a shift from a c ^1/3-dependence in dilute suspensions to a c ^1/2 behavior for higher concentrations as observed in light scattering experiments on suspensions of rodlike viruses. — In applying perturbation theory the full interaction potential is expanded with respect to a spherically symmetric reference potential. The latter has been determined according to several averaging schemes: mean potential, median potential, reference averaged Mayer potential (RAM) and the blip function method. A comparison of the results of these schemes with simulation data shows that perturbation theory provides a good description of the structure of this system only in the dilute regime.