Sensitivity of arrest in mode-coupling glasses to low-q structure

Area of Science:

• Condensed matter physics
• Materials science
• Statistical mechanics

Background:

• Understanding the relationship between liquid and glass structures is crucial.
• Mode coupling theory (MCT) provides a framework for studying the glass transition.
• The structure factor S(q) characterizes liquid and glass structures.

Purpose of the Study:

• To quantify how liquid structure changes affect glass structure using MCT.
• To investigate the sensitivity of glass structure to S(q) at different wave vectors.
• To compare these effects in repulsive and attractive glasses.

Main Methods:

• Utilizing mode coupling theory (MCT) for theoretical quantification.
• Analyzing the structure factor S(q) at various wave vectors (q).
• Focusing on the first sharp diffraction peak (q0) and lower wave vectors (e.g., q0/2).

Main Results:

• Glass structure is sensitive to S(q) around the first sharp diffraction peak (q0).
• A strong, inverted response is observed at wave vectors below q0 (e.g., q0/2).
• Increased S(q0/2) reduces the degree of glass arrest across a broad q-range, indicating weaker "caged cage" effects.

Conclusions:

• Liquid structure below the first sharp diffraction peak plays a critical role in determining glass arrest.
• Steric caging effects are strongly influenced by packing at intermediate length scales (order 2d).
• Attractive glasses exhibit weaker sensitivity to these packing effects due to dominant short-range bonding.