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 $\phi_J(\theta_0)$; \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.