Tagged-particle motion in quasi-confined colloidal hard-sphere liquids

TL;DR

This study combines mode-coupling theory and molecular dynamics simulations to analyze the motion of tagged particles in quasi-confined colloidal hard-sphere liquids, revealing complex non-monotonic behaviors and persistent anti-correlations.

Contribution

It introduces a detailed theoretical and simulation analysis of particle dynamics in quasi-confined liquids, highlighting non-monotonic mean-square displacement and long-range velocity correlations.

Findings

Non-monotonic in-plane mean-square displacement.

Persistent anti-correlations in velocity-autocorrelation function.

Negative algebraic decay $t^{-2}$ at all packing fractions.

Abstract

We investigate the tagged-particle motion in a strongly interacting quasi-confined liquid using periodic boundary conditions along the confining direction. Within a mode-coupling theory of the glass transition (MCT) we calculate the self-nonergodicity parameters and the self-intermediate scattering function and compare them with event-driven molecular dynamics simulations. We observe non-monotonic behavior for the in-plane mean-square displacement and further correlation functions which refer to higher mode indices encoding information about the perpendicular motion. The in-plane velocity-autocorrelation function reveals persistent anti-correlations with a negative algebraic power-law decay $t^{-2}$ at all packing fractions.