Colloidal bowls and platelets: stability of cubatic and worm-like fluid phases

We determine the phase behavior of hard bowls and disks, for which the colloidal analogs are respectively bowl-shaped collapsed shells and charge or sterically stabilized platelets. Both systems show significantly long stacks in the fluid for particles with intermediate thicknesses. For the platelets, the stack-rich fluid becomes a cubatic phase at large densities, while the stack-rich fluid of bowls gradually becomes more "worm-like", that is, the length and entanglement of the curved stacks increases as the density increases. We will discuss the stability of the stack-rich fluid compared to the columnar phase in both systems and compare with experiments. Finally, the rich phase behavior of these two novel systems is shown using their full phase diagrams, which are calculated using free energy calculations in Monte Carlo simulations. Apart from the columnar and (stack-rich) fluid phases mentioned before, these phase diagrams feature multiple crystal phases and (for the platelets) a nematic phase.