Analysis of the Dynamics of Liquid Aluminium: Recurrent Relation Approach

TL;DR

This paper develops a theoretical model using the recurrent relation approach to analyze the microscopic dynamics of liquid aluminium at 973 K, comparing it with hydrodynamical theories, molecular dynamics simulations, and experimental data.

Contribution

It introduces a new theoretical framework satisfying sum rules and linking high-frequency excitations with multi-particle correlations in liquid aluminium.

Findings

Dynamics mainly governed by first four even frequency moments

High-frequency excitations linked to two-, three-, and four-particle correlations

Model aligns well with experimental and simulation data

Abstract

By use of the recurrent relation approach (RRA) we study the microscopic dynamics of liquid aluminium at T=973 K and develop a theoretical model which satisfies all the corresponding sum rules. The investigation covers the inelastic features as well as the crossover of our theory into the hydrodynamical and the free-particle regimes. A comparison between our theoretical results with those following from a generalized hydrodynamical approach is also presented. In addition to this we report the results of our molecular dynamics simulations for liquid aluminium, which are also discussed and compared to experimental data. The received results reveal that (i) the microscopical dynamics of density fluctuations is defined mainly by the first four even frequency moments of the dynamic structure factor, and (ii) the inherent relation of the high-frequency collective excitations observed in experimental spectra of dynamic structure factor $S(k,\omega)$ with the two-, three- and four-particle correlations.