Decoupling phenomena in supercooled liquids: Signatures in the energy landscape

TL;DR

This paper investigates the energy landscape of supercooled liquids, identifying the onset of alpha-relaxation and the breakdown of rotational-translational coupling through changes in inherent structure energy.

Contribution

It reveals the relationship between inherent structure energy and relaxation processes, highlighting the decoupling phenomena in supercooled liquids.

Findings

Onset of alpha-process at specific energy landscape signature

Breakdown of rotational-translational coupling at lower temperature

Deviation from Debye model in orientational dynamics

Abstract

A significant deviation from the Debye model of rotational diffusion in the dynamics of orientational degrees of freedom in an equimolar mixture of ellipsoids of revolution and spheres is found to begin precisely at a temperature at which the average inherent structure energy of the system starts falling with drop in temperature. We argue that this onset temperature corresponds to the emergence of the alpha-process as a distinct mode of orientational relaxation. Equally important, we find that the coupling between the rotational and translational diffusion breaks down at a still lower temperature where a sharp change occurs in the temperature dependence of the average inherent structure energy.