标题： 基于振动模态的非仿射理论预测聚合物熔体的粘度 显示英文标题

标题： Viscosity of polymer melts using non-affine theory based on vibrational modes

摘要： 粘度是液体的基本传输和流变性质，它量化了分子层之间相对运动的阻力，并在理解材料行为中起着关键作用。 传统方法，如Green-Kubo（GK）方法，依赖于关联函数的时间积分，由于玻璃转变附近相关性衰减缓慢，计算量变得非常大。 一种基于非仿射晶格动力学（NALD）和瞬时正常模分析的新方法为估算粘度提供了一个有希望的替代方案。 在本研究中，我们将NALD方法应用于Kremer-Grest聚合物系统，在不同温度下计算粘度，并将这些结果与GK方法和非平衡分子动力学模拟的结果进行比较。 我们的研究发现，所有振动模式，包括瞬时正常模，都对粘度有贡献。 这项工作提出了一个高效的框架，用于计算各种系统中的粘度，包括玻璃转变附近，此时GK方法已不再适用。 此外，它为理解与结构相关的不同振动模式的作用开辟了途径，有助于设计具有可调流变性能的材料。 显示英文摘要

摘要： Viscosity, a fundamental transport and rheological property of liquids, quantifies the resistance to relative motion between molecular layers and plays a critical role in understanding material behavior. Conventional methods, such as the Green-Kubo (GK) approach, rely on time integration of correlation functions, which becomes computationally intensive near the glass transition due to slow correlation decay. A recently proposed method based on non-affine lattice dynamics (NALD) and instantaneous normal mode analysis offers a promising alternative for estimating the viscosity. In this study, we apply the NALD approach to compute the viscosity of the Kremer-Grest polymer system over a range of temperatures and compare these results with those from the GK method and non-equilibrium molecular dynamics simulations. Our findings reveal that all vibration modes, including the instantaneous normal modes, contribute to the viscosity. This work presents an efficient framework for calculating viscosity across diverse systems, including near the glass transition where the GK method is no longer applicable. Also, it opens the avenue to understanding the role of different vibrational modes linked with structure, facilitating the design of materials with tunable rheological properties.