Dynamic and elastic heterogeneities in a 2D model glass

A generic soft-glass prototype is considered, as the glass transition is approached. Using standard methods, and by means of Molecular Dynamics simulation, a growing critical length scale (DH) is extracted upon cooling. On the other hand, this glass is also well characterized in the low-temperature limit, from which it has been shown that its elastic response under applied deformation involves some correlated particle displacements called elastic heterogeneities (EH). We then first aim to address the connection between both lengths. As EH appear to involve some structural rearrangements, this problem then also address either the structural nature of DH or the suitability of DH to capture EH's formation. It is shown that standard methods upon cooling fail to capture the birth of EH, but mainly capture, for the lowest temperatures, fluctuations around an effective theory of elasticity for amorphous materials, in which the medium can be considered as continuous above a length scale of the order of DH. We then test a recently proposed theory of the critical slowing-down of supercooled liquids, which predicts some scaling laws for DH. Such scalings are recovered for our soft model glass. Copyright (C) EPLA, 2011