Testing "microscopic" theories of glass-forming liquids

TL;DR

This paper critically evaluates microscopic theories of glass-forming liquids based solely on static pair density correlations, revealing their failure to account for differing dynamical behaviors in similar static structures.

Contribution

It provides evidence that static pair density correlations alone are insufficient to explain the dynamical slowdown in glass-forming liquids.

Findings

Microscopic approaches fail to distinguish models with similar static correlations but different dynamics.

Static pair density correlations do not fully explain the relaxation time differences.

Results challenge the sufficiency of static structure-based theories for glass dynamics.

Abstract

We assess the validity of "microscopic" approaches of glass-forming liquids based on the sole k nowledge of the static pair density correlations. To do so we apply them to a benchmark provided by two liquid models that share very similar static pair density correlation functions while disp laying distinct temperature evolutions of their relaxation times. We find that the approaches are unsuccessful in describing the difference in the dynamical behavior of the two models. Our study is not exhausti ve, and we have not tested the effect of adding corrections by including for instance three-body density correlations. Yet, our results appear strong enough to challenge the claim that the slowd own of relaxation in glass-forming liquids, for which it is well established that the changes of the static structure factor with temperature are small, can be explained by "microscopic" appr oaches only requiring the static pair density correlations as nontrivial input.