Orientational Order in Dense Colloidal Liquids and Glasses

Area of Science:

• Physics
• Materials Science
• Chemistry

Background:

• Understanding the dynamics of dense colloidal suspensions is crucial for materials science.
• Glassy systems and supercooled liquids exhibit complex structural and dynamic behaviors.
• Conventional methods often rely on two-body structural entropy to correlate structure and dynamics.

Purpose of the Study:

• To develop novel structural order parameters for dense colloidal suspensions.
• To investigate the relationship between local structural order and local dynamics.
• To compare the predictive power of orientational order versus translational order on system dynamics.

Main Methods:

• Construction of structural order parameters using local angular and radial distribution functions.
• Analysis of correlations between these order parameters and local dynamics.
• Application of an excitation model to explain structure-dynamics correlations.

Main Results:

• All constructed order parameters correlate significantly with local dynamics in supercooled and glassy regimes.
• Correlations between orientational order and dynamical heterogeneity are stronger than those with structural entropy.
• An excitation model successfully explains structure-dynamics correlations, with energy barriers dependent on local structural order.

Conclusions:

• Local orientational order is more significant than translational order in dense disordered packings.
• Orientational order plays a dominant role in determining the dynamics of glassy systems.
• The developed order parameters provide a more accurate description of structure-dynamics relationships in colloidal glasses.