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 ${\theta }_0$. Using molecular dynamics simulations, we examine how varying ${\theta }_0$ affects their thermal solidification. By examining trends with ${\theta }_0$, comparing these to trends in trimers' jamming phenomenology, and then focusing on the six ${\theta }_0$ that are commensurable with close-packed crystalline order, we obtain three key results: \textbf{(i)} the increase in trimers' solidification temperature $T_s({\theta }_0)$ as they straighten (as ${\theta }_0\to 0^{\circ }$) is driven by the same gradual loss of \textit{effective} configurational freedom that drives athermal trimers' decreasing ${\varphi }_J({\theta }_0)$; \textbf{(ii)} ${\theta }_0$ that allow formation of both FCC and HCP order crystallize, while ${\theta }_0$ that only allow formation of HCP order glass-form; \textbf{(iii)} local cluster-level structure at temperatures slightly \textit{above} $T_s({\theta }_0)$ is highly predictive of whether trimers will crystallize or glass-form.

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