Issue 34, 2019

Mutual information does not detect growing correlations in the propensity of a model molecular liquid

Abstract

The dynamical spatial correlations detected by the mutual information (MI) in the isoconfigurational particle displacements of a monodisperse molecular viscous liquid are studied via molecular-dynamics simulations by changing considerably both the molecular mobility and the degree of dynamical heterogeneity. Different from atomic liquids, the MI correlation length does not grow on approaching the glass transition by considering the liquid both in full detail as a collection of monomers and as a coarse-grained ensemble of molecular centers of mass. In the detailed picture, it is found that: (i) the MI correlations between monomers are largely due to inter-molecular correlations, (ii) the MI length scale is numerically identical, within the errors, to the correlation length scale of the displacement direction, as drawn by conventional correlation functions. The time evolution of the MI spatial correlations complies with the scaling between the fast vibrational dynamics and the long-time relaxation. Our findings suggest that the characteristics of the MI length scale are markedly system-dependent and not obviously related to dynamical heterogeneity.

Graphical abstract: Mutual information does not detect growing correlations in the propensity of a model molecular liquid

Article information

Article type
Paper
Submitted
07 Jun 2019
Accepted
06 Aug 2019
First published
07 Aug 2019

Soft Matter, 2019,15, 6784-6790

Mutual information does not detect growing correlations in the propensity of a model molecular liquid

A. Tripodo, A. Giuntoli, M. Malvaldi and D. Leporini, Soft Matter, 2019, 15, 6784 DOI: 10.1039/C9SM01143A

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