Contribution to viscosity from the structural relaxation via the atomic scale Green-Kubo stress correlation function

Area of Science:

• Condensed Matter Physics
• Materials Science
• Computational Chemistry

Background:

• Understanding viscosity in supercooled liquids is crucial for materials science.
• Previous studies explored vibrational motion's role but not structural relaxation's direct contribution to viscosity.

Purpose of the Study:

• To investigate the link between structural relaxation and viscosity in a binary repulsive particle system.
• To determine if atomic stress auto-correlation terms can represent the viscosity contribution from structural relaxation.

Main Methods:

• Decomposition of macroscopic Green-Kubo stress correlation functions into atomic-level stress correlations.
• Analysis of parent liquid and atomic-level stress correlations.
• Comparison with inherent structure calculations.

Main Results:

• Structural relaxation's contribution to viscosity can be assessed via atomic stress auto-correlation terms.
• Vibrational contributions to viscosity persist beyond typical vibrational periods and shear wave propagation times in supercooled liquids.
• Atomic-level pressure element correlations were also investigated.

Conclusions:

• Atomic stress auto-correlation analysis provides a method to quantify structural relaxation's impact on viscosity.
• The findings enhance the understanding of dynamics in supercooled liquids.
• This approach offers a pathway to study complex liquid behaviors.