Factors influencing thermal solidification of bent-core trimers

ED Salcedo and HT Nguyen and RS Hoy, JOURNAL OF CHEMICAL PHYSICS, 151, 134501 (2019).

DOI: 10.1063/1.5121163

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 the 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: (i) the increase in trimers' solidification temperature T-s(theta(0)) as they straighten (as theta(0) -> 0 degrees) is driven by the same gradual loss of effective configurational freedom that drives athermal trimers' decreasing phi(J)(theta(0)) where phi(J)(theta(0)) is the packing fraction at jamming; (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; and (iii) local cluster-level structure at temperatures slightly above T-s(theta(0)) is highly predictive of whether trimers will crystallize or glass-form.

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