Fig. 4

Tuning of local structure in disordered and crystal-forming fluids. Disordered and crystal-forming fluids are structurally different, and tuning their fluid structure can promote or suppress crystallization. Systems are identified by α_c, indicating their location in shape space at (α_a, α_c) = (0, α_c), and the relevant location in shape space is outlined in black in the image to the right of the plots. a Twisted and aligned motif fractions, or probabilities of observing either motif, as a function of packing fraction for the disordered system at (α_a, α_c) = (0, 0.5) and nearby crystal-formers. Pink triangles represent twisted motif fractions, and red triangles represent aligned motif fractions. Different line styles indicate different locations in shape space. Crystal-forming fluids contain higher fractions of the motifs that dominate in the assembled structures. b Doping via the introduction of rigid local structural motifs into dense fluids influences assembly behavior, causing crystallization for systems that might otherwise vitrify, and vitrification for systems that otherwise crystallize. Panels show twisted motif fraction, or the probability of observing the twisted motif, for (pre-cursor) fluids during doping experiments at different locations in shape space. Symbols indicate different dopant fractions η_d. The dopant dimer is the twisted motif for α_c = 0.5 and α_c = 0.55, in which case doping promotes self-assembly into the diamond structure. For α_c = 0.4, the dopant dimer is the aligned motif, in which case doping disrupts self-assembly into the diamond structure. Symbols are colored pink if the system self-assembles into diamond on the time scales of our simulations. The threshold for assembly established by the undoped system at (α_a, α_c) = (0, 0.4) is indicated by circles connected by a black line. In all panels, error bars are smaller than the symbols, and are calculated in a manner detailed in the Precursor fluid identification section of the Methods