No Access Submitted: 20 July 2013 Accepted: 01 November 2013 Published Online: 19 December 2013
J. Chem. Phys. 139, 234505 (2013); https://doi.org/10.1063/1.4830416
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  • Alex Malins
  • Jens Eggers
  • C. Patrick Royall
Isomorphs are lines in the density-temperature plane of certain “strongly correlating” or “Roskilde simple” liquids where two-point structure and dynamics have been shown to be close to identical up to a scale transformation. Here we consider such a liquid, a Lennard-Jones glass former, and investigate the behavior along isomorphs of higher-order structural and dynamical correlations. We then consider an inverse power law reference system mapped to the Lennard-Jones system [Pedersen et al., Phys. Rev. Lett. 105, 157801 (2010)]. Using the topological cluster classification to identify higher-order structures, in both systems we find bicapped square antiprisms, which are known to be a locally favored structure in the Lennard-Jones glass former. The population of these locally favored structures is up to 80% higher in the Lennard-Jones system than the equivalent inverse power law system. The structural relaxation time of the two systems, on the other hand, is almost identical, and the four-point dynamical susceptibility is marginally higher in the inverse power law system. Upon cooling, the lifetime of the locally favored structures in the Lennard-Jones system is up to 40% higher relative to the reference system.
We thank Mark Pond and Stephen Williams for stimulating discussions at the start of this project. Bob Evans is acknowledged for his enlightening opinions on isomorphs. Jeppe Dyre is thanked for helpful comments on this work. A.M. is funded by EPSRC grant code EP/E501214/1. C.P.R. thanks the Royal Society for funding. This work was carried out using the computational facilities of the Advanced Computing Research Centre, University of Bristol.