Glassy Dynamics and Local Crystalline Order in Two-Dimensional Amorphous Silica.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Computational Chemistry

Background:

• Amorphous silica bilayers are modeled as 2D classical systems.
• Understanding the glassy dynamics and structural properties of 2D materials is crucial.
• Existing potentials require reparametrization for accurate experimental matching.

Purpose of the Study:

• To reparametrize an effective pairwise potential for amorphous silica bilayers.
• To investigate the glassy dynamics of the reparametrized model at low temperatures.
• To elucidate the relationship between structural anomalies and dynamic regimes.

Main Methods:

• Reparametrization of the Roy, Heyde, and Heuer potential.
• Simulation of glassy dynamics using cage-relative correlation functions.
• Analysis of Mermin-Wagner fluctuation effects and bond-orientational order.

Main Results:

• Quantitative matching of experimental structural details achieved.
• Two distinct Arrhenius regimes in glassy dynamics identified, separated by a crossover.
• Growth of bond-orientational order and formation of transient nanometric crystalline domains observed below the crossover.

Conclusions:

• The reparametrized model accurately captures silica bilayer behavior.
• Findings challenge the understanding of 2D glass structure and dynamics.
• Provides a framework for interpreting experimental data on 2D amorphous systems.