Columnar structures of soft spheres: Metastability and hysteresis

Previously we reported on the stable (i.e., minimal enthalpy) structures of soft monodisperse spheres in a long cylindrical channel. Here we present further simulations, which significantly extend the original phase diagram up to D/d = 2.714 (ratio of cylinder and sphere diameters), where the nature of densest sphere packing changes. However, macroscopic systems of this kind are not confined to the ideal equilibrium states of this diagram. Consequently, we explore some of the structural transitions to be expected as experimental conditions are varied; these are in general hysteretic. We represent these transitions in a stability diagram for a representative case. Illustrative videos are included in the Supplemental Material.