Factors influencing thermal solidification of bent-core trimers

Bent-core trimers are a simple model system for which the competition between crystallization and glass-formation can be tuned by varying a single parameter: the bond angle θ₀. Using molecular dynamics simulations, we examine how varying θ₀ affects their thermal solidification. By examining trends with θ₀, comparing these to the trends in trimers' jamming phenomenology, and then focusing on the six θ₀ that are commensurable with close-packed crystalline order, we obtain three key results: (i) the increase in trimers' solidification temperature T_s(θ₀) as they straighten (as θ₀ → 0°) is driven by the same gradual loss of effective configurational freedom that drives athermal trimers' decreasing ϕ_J(θ₀) [where ϕ_J(θ₀) is the packing fraction at jamming]; (ii) θ₀ that allow formation of both FCC and HCP order crystallize, while θ₀ that only allow formation of HCP order glass-form; and (iii) local cluster-level structure at temperatures slightly above T_s(θ₀) is highly predictive of whether trimers will crystallize or glass-form.