Nonperturbative effect of attractive forces in viscous liquids

TL;DR

This study uses computer simulations to investigate how attractive forces influence the structure and dynamics of viscous glass-forming liquids, revealing significant differences from systems lacking these forces.

Contribution

It demonstrates that attractive intermolecular forces significantly affect the relaxation dynamics in viscous liquids, challenging the assumption that only repulsive forces dominate.

Findings

Viscous slowing down differs markedly with and without attractive forces.

Static pair correlations are similar regardless of attractive forces.

Attractive forces play a crucial role in the relaxation behavior of viscous liquids.

Abstract

We study the role of the attractive intermolecular forces in the viscous regime of a simple glass-forming liquid by using computer simulations. To this end, we compare the structure and the dynamics of a standard Lennard-Jones glass-forming liquid model with and without the attractive tail of the interaction potentials. The viscous slowing down of the two systems are found to be quantitatively and qualitatively different over a broad density range, whereas the static pair correlations remain close. The common assumption that the behaviour of dense nonassociated liquids is determined by the short-ranged repulsive part of the intermolecular potentials dramatically breaks down for the relaxation in the viscous liquid regime.