Structural Relaxation of a Gel Modeled by Three Body Interactions

TL;DR

This study uses molecular dynamics simulations to explore a low-density gel model with modified three-body interactions, revealing ballistic chain segment motion causes compressed exponential relaxation.

Contribution

It introduces a modified three-body potential for gel modeling and uncovers the ballistic motion mechanism behind relaxation dynamics.

Findings

Reduced coordination number suppresses phase coexistence.

Gel exhibits compressed exponential relaxation.

Chain segment motion is ballistic without network restructuring.

Abstract

We report a molecular dynamics simulation study of a model gel whose interaction potential is obtained by modifying the three body Stillinger-Weber model potential for silicon. The modification reduces the average coordination number, and suppresses the liquid-gas phase coexistence curve. The low density, low temperature equilibrium gel that can thus form exhibits interesting dynamical behavior, including compressed exponential relaxation of density correlations. We show that motion responsible for such relaxation has ballistic character, and arises from the motion of chain segments in the gel without the restructuring of the gel network.