Factors influencing thermal solidification of bent-core trimers.

Abstract

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 Ts(θ0) as they straighten (as θ0 → 0°) is driven by the same gradual loss of effective configurational freedom that drives athermal trimers' decreasing ϕJ(θ0) [where ϕJ(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 Ts(θ0) is highly predictive of whether trimers will crystallize or glass-form.