Contribution of transverse modes to the dynamics of density fluctuations

TL;DR

This paper investigates how transverse modes influence density fluctuation dynamics in sodium, using simulations and experiments, revealing significant agreement and supporting the Vibration-Transit theory.

Contribution

It provides a comparative analysis of transverse current spectra in sodium through simulations and experiments, highlighting the role of transverse modes in liquid dynamics.

Findings

Good agreement between simulation and experimental spectra

Transverse modes significantly affect density fluctuations

Supports Vibration-Transit theory of liquid dynamics

Abstract

The transverse and longitudinal current correlation functions are evaluated in liquid and amorphous sodium by computer simulation. The study of the corresponding spectra as a function of the wavevector $k$ allows the evaluation of a dispersion curve for their peak position. The results are compared with recent experimental findings [PNAS 107, 21985 (2010)], obtained by a new analysis of $S(k,{\omega})$ measured by inelastic X-ray scattering in liquid and polycrystalline sodium. A substantial agreement between experimental and computer simulation results is found. The analysis of the line widths supports the Vibration-Transit theory picture of the dynamics in liquids.