Striking Similarities in Dynamics and Vibrations of 2D Quasicrystals and Supercooled Liquids

TL;DR

This study reveals that two structurally different 2D systems, a quasicrystal and a supercooled liquid, exhibit similar dynamical behaviors despite their structural differences, with distinct vibrational properties.

Contribution

It demonstrates the universality of dynamical similarities across diverse 2D systems and explores their vibrational and topological differences.

Findings

Both systems show dynamic heterogeneities and structure-dynamics correlations.

Vibrational properties differ: quasicrystal has phason-related peaks, supercooled liquid has a boson peak.

Extended vibrational modes are present at low frequencies in both systems.

Abstract

We investigate the interplay between structure and dynamics in two structurally distinct two-dimensional systems: a dodecagonal quasicrystal (DDQC) and a supercooled binary liquid. Using molecular dynamics simulations, we uncover striking dynamical similarities despite their fundamentally different structural organizations. Both systems exhibit pronounced dynamic heterogeneities, as evidenced by the cage-trapping plateaus in the mean-squared displacement and the pronounced peaks in the non-Gaussian parameter. In both cases, we observe a strong correlation between local structural order and dynamic propensity, indicating similar structure-dynamics relationships, albeit driven by distinct microscopic mechanisms. Despite these parallels, their vibrational properties diverge: the DDQC exhibits multiple peaks linked to phason dynamics, while the supercooled liquid displays a characteristic boson peak. Analysis of vibrational eigenmodes shows that both systems exhibit extended modes at low frequencies. At high frequencies, however, the DDQC maintains a higher density of topological defects, reflecting its quasi-long-range order. Finally, we contextualize these findings by comparing both systems to a square crystal. While the dynamics appears similar across all three systems, the vibrational and topological features clearly distinguish the DDQC and glass from the crystalline state. These results underscore a surprising universality in dynamical behavior across structurally diverse systems and provide new insights into how structural organization shapes motion in soft-matter systems.