A semi-schematic model for the center of mass dynamics in supercooled molecular liquids

TL;DR

This paper presents a semi-schematic mode-coupling model focusing on the center of mass dynamics in supercooled molecular liquids, successfully capturing key static and dynamic features across various q-vectors.

Contribution

It introduces a simplified model that explicitly describes only the center of mass degrees of freedom, effectively approximating angular effects through a coupling parameter.

Findings

Model accurately reproduces static and dynamic relaxation features.

Good agreement with molecular dynamics simulation data.

Applicable across a broad q-vector range.

Abstract

We introduce a semi-schematic mode-coupling model to describe the slow dynamics in molecular liquids, retaining explicitly only the description of the center of mass degrees of freedom. Angular degrees of freedom are condensed in a q-vector independent coupling parameter. We compare the time and q-dependence of the density fluctuation correlators with numerical data from a 250 ns long molecular dynamics simulation. Notwithstanding the choice of a network-forming liquid as a model for comparing theory and simulation, the model describes the main static and dynamic features of the relaxation in a broad q-vector range.