Relation between dynamic heterogeneities observed in scattering experiments and four-body correlations

TL;DR

This paper explores the connection between dynamic heterogeneities observed in scattering experiments and four-body correlations, aiming to clarify their physical relationship near the glass transition.

Contribution

It proposes and validates a link between dynamic heterogeneities from speckle patterns and four-body correlations, unifying different evaluation methods.

Findings

Established a quantitative relationship between speckle pattern heterogeneities and four-body correlations.

Validated the proposed connection through theoretical analysis.

Enhanced understanding of slow dynamics near the glass transition.

Abstract

Dynamic heterogeneity is expected to be a key concept for understanding the origin of slow dynamics near the glass transition. In previous studies, quantitative evaluations of dynamic heterogeneity have been attempted using two different routes, i.e., the speckle patterns in scattering experiments or the four-body correlation functions of microscopic configuration data obtained from molecular dynamics simulations or real-space observations using confocal microscopy. However, the physical relationship between these dynamic heterogeneities obtained using different methods has not been clarified. This study proposes a connection between dynamic heterogeneities characterized based on speckle patterns and those obtained from four-body correlations. The validity of the relationship is also clarified.