Density oscillations in multi-component molecular mixtures

TL;DR

This paper investigates the excitation spectrum of density oscillations in multi-component molecular mixtures, revealing distinct sound-like modes influenced by short-range interactions and explaining the two-sounds phenomenon.

Contribution

It introduces a model that predicts and explains the two-sounds phenomenon in multi-component molecular mixtures with Coulomb and short-range interactions.

Findings

Identification of distinct sound-like excitations governed by short-range interactions

Calculation of dielectric function and structure factor for these mixtures

Explanation of the two-sounds phenomenon through the model

Abstract

The excitation spectrum of the density collective oscillations is computed for multi-component molecular mixtures both with Coulomb and (repulsive) short-range interactions. Distinct sound-like excitations appear, governed by the short-range interaction, which differ from the ordinary hydrodynamic sound. The dielectric function and the structure factor are also calculated. The "two-sounds phenomenon" can be understood by means of the predictions of this model.