Melting driven by particle size-dispersity: a study in two dimensions

We study the effect of particle size-dispersity on solids and melting of solids by molecular dynamics simulation on a two-dimensional size-dispersed Lennard-Jones system. We find that size-dispersity disfavours solidification and on increasing the dispersity, the solid ‘melts’, at a critical dispersity, to a liquid. The solid–liquid transition depends on the density — the transition is continuous through the ‘hexatic’ phase at low densities and abrupt first order transition at higher densities. We find that size-dispersity creates topological defects in the close-pack solid structure which destroy the crystalline order in solids.