Isolating long-wavelength fluctuation from structural relaxation in two-dimensional glass: Cage-relative displacement

Hayato Shiba, Peter Keim, Takeshi Kawasaki

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


It has recently been revealed that long-wavelength fluctuation exists in two-dimensional (2D) glassy systems, having the same origin as that given by the Mermin-Wagner theorem for 2D crystalline solids. In this paper, we discuss how to characterise quantitatively the long-wavelength fluctuation in a molecular dynamics simulation of a lightly supercooled liquid. We employ the cage-relative mean-square displacement (MSD), defined on relative displacement to its cage, to quantitatively separate the long-wavelength fluctuation from the original MSD. For increasing system size the amplitude of acoustic long wavelength fluctuations not only increases but shifts to later times causing a crossover with structural relaxation of caging particles. We further analyse the dynamic correlation length using the cage-relative quantities. It grows as the structural relaxation becomes slower with decreasing temperature, uncovering an overestimation by the four-point correlation function due to the long-wavelength fluctuation. These findings motivate the usage of cage-relative MSD as a starting point for analysis of 2D glassy dynamics.

Original languageEnglish
Article number094004
JournalJournal of Physics Condensed Matter
Issue number9
Publication statusPublished - 2018 Feb 12


  • colloids
  • dynamic correlation length
  • low-dimensional system
  • molecular dynamics simulation
  • slow glassy relaxation

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics


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