Viscoelastic relaxation and topological fluctuations in glass-forming liquids

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

A method for characterizing the topological fluctuations in liquids is proposed. This approach exploits the concept of the weighted gyration tensor of a collection of particles and permits the definition of a local configurational unit (LCU). The first principal axis of the gyration tensor serves as the director of the LCU, which can be tracked and analyzed by molecular dynamics simulations. Analysis of moderately supercooled Kob-Andersen mixtures suggests that orientational relaxation of the LCU closely follows viscoelastic relaxation and exhibits a two-stage behavior. The slow relaxing component of the LCU corresponds to the structural, Maxwellian mechanical relaxation. Additionally, it is found that the mean curvature of the LCUs is approximately zero at the Maxwell relaxation time with the Gaussian curvature being negative. This observation implies that structural relaxation occurs when the configurationally stable and destabilized regions interpenetrate each other in a bicontinuous manner. Finally, the mean and Gaussian curvatures of the LCUs can serve as reduced variables for the shear stress correlation, providing a compelling proof of the close connection between viscoelastic relaxation and topological fluctuations in glass-forming liquids.

Original languageEnglish
Article number094506
JournalJournal of Chemical Physics
Volume160
Issue number9
DOIs
StatePublished - Mar 7 2024

Funding

This research was supported, in part, by the Spallation Neutron Source, a U.S. Department of Energy Office of Science User Facility at the Oak Ridge National Laboratory. The computer simulations were conducted as part of a user project at the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy Office of Science User Facility at Oak Ridge National Laboratory. C.-H.T. and S.-Y.C. acknowledge the support from the Ministry of Science and Technology of Taiwan under Grant No. MOST 108-2221-E007-054-MY3. B.G.S. acknowledges the support from the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences Data, Artificial Intelligence and Machine Learning at DOE Scientific User Facilities Program, under Award No. 34532. Y.W. was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Early Career Research Program Award No. KC0402010, under Contract No. DE-AC05-00OR22725. Y.S. was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Science and Engineering Division. We acknowledge the National Center for High-Performance Computing of Taiwan for providing computational and storage resources.

Fingerprint

Dive into the research topics of 'Viscoelastic relaxation and topological fluctuations in glass-forming liquids'. Together they form a unique fingerprint.

Cite this