We present evidence from computer simulations for glassy dynamics in suspensions of monodisperse hard ellipsoids. In equilibrium, almost spherical ellipsoids show a first-order transition from an isotropic phase to a rotator phase. When overcompressing the isotropic phase into the rotator regime, we observe super-Arrhenius slowing-down of diffusion and relaxation, accompanied by two-step relaxation in positional and orientational correlators. The effects are strong enough for asymptotic laws of mode-coupling theory to apply. Glassy dynamics are unusual in monodisperse systems. Typically, polydispersity in size, a mixture of particle species or networkforming covalent bonds are prerequisite to prevent crystallization. Here, we show that a slight particle anisometry acts as a sufficient source of disorder. This sheds new light on the question of which ingredients are required for glass formation.

We present the phase diagram of hard snowman-shaped particles calculated using Monte Carlo simulations and free energy calculations. The snowman particles consist of two hard spheres rigidly attached at their surfaces. We find a rich phase behavior with isotropic, plastic crystal, and aperiodic crystal phases. The crystalline phases found to be stable for a given sphere diameter ratio correspond mostly to the close packed structures predicted for equimolar binary hard-sphere mixtures of the same diameter ratio. However, our results also show several crystal-crystal phase transitions, with structures with a higher degree of degeneracy found to be stable at lower densities, while those with the best packing are found to be stable at higher densities.

Using Monte Carlo simulations and free energy calculations, we study the phase behavior of hard asymmetric dumbbell particles with a constituent sphere diameter ratio of 0.5. We find a rich phase behavior with isotropic fluid, rotator, and periodic NaCl-based and both periodic and aperiodic CrB-based crystalline phases. The rotator phases found to be stable in this study are similar to those found in systems of snowman-shaped and dumbbell particles and we investigate the behavior of these phases by comparing their stability ranges, and by looking at the orientational reorganization of particles. We also find that the NaCl-based crystalline phase can expand its range of stability by undergoing a slight modification which allows it to pack better. Finally, we see that reducing the sphere separation results in the aperiodic crystalline phases becoming destabilized as compared to the phase behavior of snowman-shaped particles.

We present evidence from computer simulations for glassy dynamics in suspensions of monodisperse hard ellipsoids. In equilibrium, almost spherical ellipsoids show a first order transition from an isotropic phase to a rotator phase. When overcompressing the isotropic phase into the rotator regime, we observe super-Arrhenius slowing down of diffusion and relaxation, accompanied by two-step relaxation in positional and orientational correlators. The effects are strong enough for asymptotic laws of mode-coupling theory to apply. Glassy dynamics are unusual in monodisperse systems. Typically, polydispersity in size or a mixture of particle species is prerequisite to prevent crystallization. Here, we show that a slight particle anisometry acts as a sufficient source of disorder. This sheds new light on the question of which ingredients are required for glass formation.

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