8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Thu 811:10-14:00P8.27Using the topological cluster classification to identifyslow clusters within supercooled liquidsAlex Malins, 1 C. Patrick Royall, 1 Jens Eggers, 2 Stephen Williams, 3 and HajimeTanaka 41 Bristol Centre for Complexity Sciences, The School of Chemistry, University of BristolBS8 1TS, Bristol, United Kingdom2 The Department of Mathematics, Bristol, United Kingdom3 Research School of Chemistry, Canberra, Australia4 The University of Tokyo, Tokyo, JapanRecently it has been suggested that the population of small clusters of particles with definedgeometries can increase dramatically on cooling of supercooled liquids below the onset temperatureT x [1]. In this research we employ the Topological Cluster Classification algorithm(TCC) [2, 3] to characterize the static distribution of clusters in Kob-Anderson, Wahnstrom andother binary supercooled liquids, and extend this algorithm to examine the dynamics of clusters.Firstly, we correlate the regions of the liquids displaying slow dynamics with the static clusterdistributions. We then develop a dynamic implementation of the TCC to measure the lifetimes ofclusters in order to demonstrate the converse result, namely that slowly relaxing regions of thesupercooled liquid can be identified by regions populated by long lifetime clusters, and not just interms of individual particle dynamics. The results show that although the clusters that increase inprevalence below the onset temperature T x display a mean lifetime of the order of the structuralrelaxation time τ α , the distribution of lifetimes is such that a significant proportion of theseclusters may have relatively short lifetimes, while a subset in the tail of the distribution exhibitlifetimes many multiples of τ α . This result encourages us to distinguish between the short-livedand long-lived clusters by examining the distributions of A and B type species on the surface ofthe clusters.[1] D. Coslovich, G. Pastore, J. Chem. Phys. 127, 124504 (2007).[2] S. R. Williams, arXiv, 0705. 0203 (2007).[3] C. P. Royall, S. R. Williams, T. Ohtsuka, H. Tanaka, Nature materials 7, 556 (2008).27