2014 Theses Doctoral

Connections between structure and dynamics in model supercooled liquids

Hocky, Glen Max

In this thesis, we examine the relationship between structure and dynamics in supercooled liquids from five unique perspectives. We first study a static length scale in the liquid and compare its growth on decreasing temperature with the growth of the logarithm of relaxation times, and find them to be almost strongly correlated. We find that this length scale can distinguish between several specially chosen model liquids whose structure at the level of two-body correlations are identical but whose dynamics at a given temperature are quite different. We then study the number of normal modes necessary to capture the rearrangements in a two-dimensional supercooled liquid as it moves between inherent structures. We find that the number of modes is quite small and decreases as the system is further cooled. After that, we study the effect of a frozen amorphous boundary on the dynamics of supercooled liquids and find that the range of the effect plateaus near that system's mode coupling temperature. We also identify a dynamical crossover at a higher temperature from these data by contrasting the relaxation behavior in the directions perpendicular and parallel to the boundary. After this work, we compare particle mobility with the position of particles deemed to be in preferred local packing arrangements. We find that the correlation between slow dynamics and the location of these locally preferred structures is highly dependent on the model investigated. Finally, we study supercooled liquids that have a fraction of particles randomly fixed in equilibrium positions. We find from annealing and rapid heating experiments on these samples behavior reminiscent of experimentally produced ultrastable glasses.