Microscopic Theory for the Role of Attractive Forces in the Dynamics of Supercooled Liquids

TL;DR

This paper develops a microscopic theory explaining how attractive and repulsive forces influence the slow dynamics of supercooled liquids, predicting behaviors consistent with recent experiments and simulations.

Contribution

It introduces a no-parameter microscopic framework that accounts for the effects of attractive forces on supercooled liquid dynamics under different thermodynamic conditions.

Findings

Attractive forces significantly affect slow dynamics under isochoric conditions.

At high densities, the influence of attractive forces diminishes.

The theory predicts high-temperature Arrhenius behavior and density-temperature scaling.

Abstract

We formulate a microscopic, no adjustable parameter, theory of activated relaxation in supercooled liquids directly in terms of the repulsive and attractive forces within the framework of pair correlations. Under isochoric conditions, attractive forces can nonperturbatively modify slow dynamics, but at high enough density their influence vanishes. Under isobaric conditions, attractive forces play a minor role. High temperature apparent Arrhenius behavior and density-temperature scaling are predicted. Our results are consistent with recent isochoric simulations and isobaric experiments on a deeply supercooled molecular liquid. The approach can be generalized to treat colloidal gelation and glass melting, and other soft matter slow dynamics problems.