Crossover behavior and multistep relaxation in a schematic model of the cut-off glass transition

Greenall, M. J. and Cates, M. E. (2007) Crossover behavior and multistep relaxation in a schematic model of the cut-off glass transition. Physical Review E, 75 (5). 051503. ISSN 2470-0045

0702170.pdf - Whole Document

Item Type:Article
Item Status:Live Archive


We study a schematic mode-coupling model in which the ideal glass transition is cut off by a decay of the quadratic coupling constant in the memory function. (Such a decay, on a time scale τI, has been suggested as the likely consequence of activated processes.) If this decay is complete, so that only a linear coupling remains at late times, then the α relaxation shows a temporal crossover from a relaxation typical of the unmodified schematic model to a final strongly slower-than-exponential relaxation. This crossover, which differs somewhat in form from previous schematic models of the cutoff glass transition, resembles light-scattering experiments on colloidal systems, and can exhibit a “slower-than-α” relaxation feature hinted at there. We also consider what happens when a similar but incomplete decay occurs, so that a significant level of quadratic coupling remains for t⪢τI. In this case the correlator acquires a third, weaker relaxation mode at intermediate times. This empirically resembles the β process seen in many molecular glass formers. It disappears when the initial as well as the final quadratic coupling lies on the liquid side of the glass transition, but remains present even when the final coupling is only just inside the liquid (so that the α relaxation time is finite, but too long to measure). Our results are suggestive of how, in a cutoff glass, the underlying “ideal” glass transition predicted by mode-coupling theory can remain detectable through qualitative features in dynamics.

Keywords:Glass transition
Subjects:F Physical Sciences > F300 Physics
Divisions:College of Science > School of Mathematics and Physics
Related URLs:
ID Code:22428
Deposited On:04 Mar 2016 20:16

Repository Staff Only: item control page