Light-Scattering by Longitudinal phonons in Supercooled Molecular Liquids II: Microscopic Derivation of the Phenomenological Equations

TL;DR

This paper derives microscopic constitutive equations for the orientational dynamics of linear molecules in supercooled liquids, linking them to phenomenological models and providing exact expressions for key coefficients.

Contribution

It offers a microscopic derivation of the phenomenological equations governing molecular orientation in supercooled liquids, clarifying the origin of phenomenological coefficients.

Findings

Derived generalized Langevin equations match phenomenological models

Provided formal exact expressions for phenomenological coefficients

Showed constraints arise naturally from microscopic theory

Abstract

The constitutive equations for the orientational dynamics of a liquid formed of linear molecules are derived microscopically. The resulting generalised Langevin equations coincide with the phenomenological approach of Dreyfus et al. Formally exact expressions are given for the phenomenological coefficients and various constraints are shown to be consequences of this microscopic approach.