Ten themes of viscous liquid dynamics

TL;DR

This paper discusses ten key themes in viscous liquid physics, proposing a general theoretical framework based on time-dependent Ginzburg-Landau equations that captures equilibrium dynamics and explains observed long-range correlations.

Contribution

It introduces a unified theoretical approach to viscous liquid dynamics using Ginzburg-Landau equations, emphasizing long-wavelength dominance and non-conserved density fields.

Findings

Density acts as a non-conserved field.

Dynamics are dominated by long wavelengths.

Long-ranged dynamic correlations exist on the alpha time scale.

Abstract

Ten "themes" of viscous liquid physics are discussed with a focus on how they point to a general description of equilibrium viscous liquid dynamics (i.e., fluctuations) at a given temperature. This description is based on standard time-dependent Ginzburg-Landau equations for the density fields, stress tensor fields, potential energy density field, and fields quantifying molecular orientations. One characteristic aspect of the theory is that density has the appearance of a non-conserved field. Another characteristic feature is long-wavelength dominance of the dynamics, which not only simplifies the theory by allowing for an ultra-local Hamiltonian (free energy), but also explains the observed general independence of chemistry. Whereas there are no long-ranged static (i.e., equal-time) correlations in the model, there are important long-ranged dynamic correlations on the alpha time scale.