Speaker
Description
Quasicrystals are one of the most intriguing phases in classical matter. Defying the normal constraint of periodicity that applies to normal crystal structures, they can exhibit rotational symmetries that are forbidden for periodic crystals, e.g. 10-, 12-, 18-, 20-fold symmetries. These symmetries can be easily recognized in their diffraction patterns -- and it is this characteristic that led to their original discovery by Dan Shechtman in 1984. While quasicrystals were first found in atomic systems, they have since been found in a growing number of soft-matter systems, including nanoparticles, polymers, and micelles. How simple can a system be and still exhibit such an atypical, complex phase? Why does such a phase form in the first place? In this talk I will address these questions, and many others regarding the appearance of quasicrystals in soft matter. In particular, I will show how even a simple system of hard spheres can be designed to form quasicrystals. Using a combination of event driven molecular dynamics simulations and free energy calculations, I will discuss the huge importance of entropy in their stabilization, and end the talk by delving into the appearance of point defects in these systems.
