ABSTRACT We discuss the role of non-hydrodynamic processes in viscoelastic transition in pure liquids. In particular, using both analytical results and molecular dynamics simulations, we clarify the effect of the shear stress relaxation on the transverse dynamics. We use as an example the Lennard-Jones fluids. We analyse the frequency dependence of the shear modulus and its connection to the non-hydrodynamic shear relaxation mode. The analysis of the relaxation times of the non-hydrodynamic modes in longitudinal and transverse dynamics makes evidence that the emergence of the non-hydrodynamic transverse excitations outside the propagation gap is not directly connected to the onset of the positive sound dispersion.

中文翻译：

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简单流体粘弹性行为中的非流体动力模式

摘要 我们讨论了非流体动力学过程在纯液体粘弹性转变中的作用。特别是，使用分析结果和分子动力学模拟，我们阐明了剪切应力松弛对横向动力学的影响。我们以 Lennard-Jones 流体为例。我们分析了剪切模量的频率依赖性及其与非流体力学剪切松弛模式的联系。纵向和横向动力学中非流体动力学模式的弛豫时间分析表明，传播间隙外非流体动力学横向激励的出现与正声分散的开始没有直接关系。