Comparison of Linear Viscoelastic Behaviors of Langevin- and Jump-Rouse Models

Fuente: arXiv
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Main Author: Uneyama, Takashi
Format: Preprint
Published: 2023
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author Uneyama, Takashi
author_facet Uneyama, Takashi
contents The Rouse model with harmonic springs and the Langevin equation (Langevin-Rouse model) is widely used to describe the linear viscoelasticity of unentangled polymer melts. A similar model, in which the Langevin equation is replaced by discrete local jump dynamics (the jump-Rouse model), is also used to describe the dynamics of some systems such as entangled polymer melts. Intuitively, we expect that the Langevin- and jump-Rouse models give similar linear viscoelastic behaviors. However, the Langevin- and jump-Rouse models are not equivalent, and their linear viscoelastic behaviors can be different. In this work, we compare the shear relaxation moduli of the Langevin- and jump-Rouse model in detail. We develop a jump rate model in which the resampling ratio is tunable. By using this jump rate model, we can smoothly connect the jump-Rouse model and the Langevin-Rouse model. We perform kinetic Monte Carlo simulations to calculate the shear relaxation modulus data of the jump-Rouse model. We compare the simulation results with various numbers of beads and resampling ratios, and show that the shear relaxation moduli of the Langevin- and jump-Rouse models are similar but slightly different. We analyze the short-time relaxation behavior of the jump-Rouse model, and show that the local jumps give a single Maxwell type relaxation in the short-time region.
format Preprint
id arxiv_https___arxiv_org_abs_2312_02402
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Comparison of Linear Viscoelastic Behaviors of Langevin- and Jump-Rouse Models
Uneyama, Takashi
Soft Condensed Matter
The Rouse model with harmonic springs and the Langevin equation (Langevin-Rouse model) is widely used to describe the linear viscoelasticity of unentangled polymer melts. A similar model, in which the Langevin equation is replaced by discrete local jump dynamics (the jump-Rouse model), is also used to describe the dynamics of some systems such as entangled polymer melts. Intuitively, we expect that the Langevin- and jump-Rouse models give similar linear viscoelastic behaviors. However, the Langevin- and jump-Rouse models are not equivalent, and their linear viscoelastic behaviors can be different. In this work, we compare the shear relaxation moduli of the Langevin- and jump-Rouse model in detail. We develop a jump rate model in which the resampling ratio is tunable. By using this jump rate model, we can smoothly connect the jump-Rouse model and the Langevin-Rouse model. We perform kinetic Monte Carlo simulations to calculate the shear relaxation modulus data of the jump-Rouse model. We compare the simulation results with various numbers of beads and resampling ratios, and show that the shear relaxation moduli of the Langevin- and jump-Rouse models are similar but slightly different. We analyze the short-time relaxation behavior of the jump-Rouse model, and show that the local jumps give a single Maxwell type relaxation in the short-time region.
title Comparison of Linear Viscoelastic Behaviors of Langevin- and Jump-Rouse Models
topic Soft Condensed Matter
url https://arxiv.org/abs/2312.02402