Symmetries in hard polygon systems determine plastic colloidal crystal mesophases in two dimensions. Issue 12 (4th March 2019)

• Record Type: Journal Article
• Authors: Shen, Wenbo; Antonaglia, James; Anderson, Joshua A.; Engel, Michael; van Anders, Greg; Glotzer, Sharon C.
• Is Part Of: Soft matter. Volume 15:Issue 12(2019)
• Page Start: 2571
• Page End: 2579
• Publication Date: 2019-03-04
• Subjects: Soft condensed matter -- Periodicals; 530.413
• DOI: 10.1039/c9sm00016j
• Languages: English
• ISSNs: 1744-683X

Abstract

Abstract : Symmetry arguments explain the appearance of new and old plastic crystal mesophases in hard regular polygons. Abstract : Orientational ordering is a necessary step in the crystallization of molecules and anisotropic colloids. Plastic crystals, which are possible mesophases between the fluid and fully ordered crystal, are translationally ordered but exhibit no long range orientational order. Here, we study the two-dimensional phase behavior of hard regular polygons with edge number n = 3–12. This family of particles provides a model system to isolate the effect of shape and symmetry on the existence of plastic crystal phases. We show that the symmetry group of the particle, G, and the symmetry group of the local environment in the crystal, H, together determine plastic colloidal crystal phase behavior in two dimensions. If G contains completely the symmetry elements of H, then a plastic crystal phase is absent. If G and H share some but not all nontrivial symmetry elements, then a plastic crystal phase exists with preferred particle orientations that recover the absent symmetry elements of the crystal; we call this phase the discrete plastic crystal phase. If G and H share no nontrivial symmetry elements, then a plastic crystal phase exists without preferred orientations, which we call an indiscrete plastic crystal.