By: Vera Batista
At: Instituto de Investigação Interdisciplinar, Anfiteatro
The interactions between colloidal particles can often be described by simple potentials, making many experimentally observed colloids amenable to investigation through analytic theory and computer simulation. In this talk I will address the effect of internal flexibility which is relevant to several types of colloids including globular proteins, micelles and emulsions. I will introduce and characterize a model for a generic class of colloidal particles that have a preferred shape but can undergo deformations while always maintaining hardâ€“body interactions.
The model consists of hard spheres that can continuously change shape at fixed volume into prolate or oblate ellipsoids of revolution, subject to an energetic penalty. The severity of this penalty is specified by a single parameter that determines the flexibility of the particles. The deformable hard spheres crystallize at higher packing fractions than rigid hard spheres, have a narrower solidâ€“fluid coexistence region and can reach high densities by a second transition to an orientationally ordered crystal. I will also address the effect of flexibility on the packing properties of deformable ellipsoids of revolution.