Impact of elastic heterogeneity on the propagation of vibrations at 1nite temperatures in glasses

Abstract

Some aspects of how sound waves travel through disordered solids are still unclear. Recent work has characterized a feature of disordered solids which seems to in2uence vibrational excitations at the mesoscales, local elastic heterogeneity. Sound waves propagation has been demonstrated to be strongly affected by inhomogeneous mechanical features of the materials which add to the standard anharmonic couplings, amounting to extremely complex transport properties at 1nite temperatures. Here, we address these issues for the case of a simple atomic glass former, by Molecular Dynamics computer simulation. In particular, we focus on the transverse components of the vibrational excitations in terms of dynamic structure factors, and characterize the temperature dependence of sound dispersion and attenuation in an extended frequency range. We provide a complete picture of how elastic heterogeneity determines transport of vibrational excitations, also based on a direct comparison of the numerical data with the predictions of the heterogeneous elastic theory.