Although bead microrheology experiments are routinely used to characterize the viscoelasticity of complex matter, their simulation analog—probe rheology molecular simulations—has been scarcely used since the system characteristics required for its robust implementation are not established in the literature. We address this issue by analyzing an active probe rheology simulation setup consisting of a probe particle that is subjected to an external oscillatory force and a harmonic trapping force. We identify a set of eight conditions of the system properties that must be satisfied for the successful implementation of the probe rheology technique in molecular simulations. Among these criteria, the two most important are as follows: (1) The spring force constant for the trapping force should be sufficiently large such that the peak in the Fourier transform of the probe displacement occurs at the same frequency as that of the applied force. (2) System parameters should be chosen such that the magnitude of the external force used to drive the probe motion should be comparable to the magnitude of the hydrodynamic friction force experienced by the probe particle in the viscoelastic medium. Furthermore, a scaling relation that can be used to determine the frequency at which inertial effects set in for a given probe size is also established. The validity of our procedure is demonstrated by applying it to determine the viscoelastic properties of a weakly entangled polymer melt system.

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确定软物质粘弹性模量的主动探针流变模拟技术的实现

尽管珠子微流变实验通常用于表征复杂物质的粘弹性，但它们的模拟模拟——探针流变学分子模拟——很少使用，因为文献中没有建立其稳健实施所需的系统特性。我们通过分析由受到外部振荡力和谐波俘获力的探针粒子组成的主动探针流变模拟设置来解决这个问题。我们确定了在分子模拟中成功实施探针流变技术必须满足的系统特性的一组八个条件。在这些标准中，最重要的两个标准如下：(1) 捕获力的弹簧力常数应该足够大，以便探针位移的傅立叶变换峰值出现在与施加力相同的频率上。(2) 系统参数的选择应使得用于驱动探针运动的外力的大小应与探针粒子在粘弹性介质中所经历的流体动摩擦力的大小相当。此外，还建立了可用于确定针对给定探头尺寸设置的惯性效应频率的比例关系。我们的程序的有效性通过应用它来确定弱缠结聚合物熔体系统的粘弹性来证明。(2) 系统参数的选择应使得用于驱动探针运动的外力的大小应与探针粒子在粘弹性介质中所经历的流体动摩擦力的大小相当。此外，还建立了可用于确定针对给定探头尺寸设置的惯性效应频率的比例关系。我们的程序的有效性通过应用它来确定弱缠结聚合物熔体系统的粘弹性来证明。(2) 系统参数的选择应使得用于驱动探针运动的外力大小应与探针粒子在粘弹性介质中所经历的流体动摩擦力的大小相当。此外，还建立了可用于确定针对给定探头尺寸设置的惯性效应频率的比例关系。我们的程序的有效性通过应用它来确定弱缠结聚合物熔体系统的粘弹性来证明。还建立了一个比例关系，可用于确定为给定探头尺寸设置的惯性效应的频率。我们的程序的有效性通过应用它来确定弱缠结聚合物熔体系统的粘弹性来证明。还建立了一个比例关系，可用于确定为给定探头尺寸设置的惯性效应的频率。我们的程序的有效性通过应用它来确定弱缠结聚合物熔体系统的粘弹性来证明。