Long ranged stress correlations in the hard sphere liquid

Area of Science:

• Condensed matter physics
• Materials science
• Statistical mechanics

Background:

• The liquid-to-glass transition is characterized by the emergence of shear elasticity.
• In solids, stresses around inclusions follow an Eshelby power law (r-D).
• Understanding stress dynamics in liquids is crucial for explaining glassy behavior.

Purpose of the Study:

• To investigate the emergence of Eshelby-like power-law stress correlations in glass-forming liquids.
• To analyze the spatial and temporal behavior of stress fields during the liquid-glass transition.
• To connect stress relaxation mechanisms to material properties like shear modulus and friction.

Main Methods:

• Molecular dynamics simulations of glass-forming hard sphere fluids.
• Detailed tensorial analysis of stress correlations.
• Examination of fluctuating force fields and shear stress dynamics.

Main Results:

• Observed unscreened power-law Eshelby patterns (r-D) in the stress correlations of the isotropic liquid state.
• Demonstrated that fluctuating force fields relax to zero, while shear stress correlations form power-law structures.
• Identified spatial regions where these structures grow with sound propagation, exhibiting exponents r-D and r-D-2.
• Showed that shear stresses relax diffusively within these regions in Brownian systems.

Conclusions:

• Glass-forming liquids exhibit solid-like stress correlation patterns prior to complete solidification.
• The emergence of these patterns is linked to sound propagation dynamics.
• Diffusive relaxation of shear stress is governed by shear modulus and friction in Brownian systems.