Aggregation in Quenched Systems Interacting through a Short-Range Attractive, Long-Range Repulsive Potential

Abstract

The morphology and structure factor of a 2D system of particles interacting through a Lennard-Jones potential, modified to include a long-range repulsive component, are described. Of particular interest are those systems quenched from a stabilized colloidal state to temperatures that, in the pure Lennard-Jones system, correspond to the solid-vapor coexistence region. We find that competition between the short-range attractive forces—which cause aggregation—and the long-range repulsion—which acts to keep the particles apart—encourages the formation of space-filling networks. A characteristic peak in the structure factor is observed which moves toward lower wavevectors as the simulation evolves. However, unlike the pure Lennard-Jones system, which when given enough time will completely phase separate, this peak stops moving once a network has formed. The similarities between our simulations and gel formation are discussed.