Dynamics of uniaxial hard ellipsoids

TL;DR

This study investigates the translational and rotational dynamics of monodisperse hard ellipsoids using a new molecular dynamics algorithm, revealing decoupled diffusion behaviors and glassy dynamics influenced by aspect ratio and volume fraction.

Contribution

Introduces a novel event-driven molecular dynamics algorithm to analyze the dynamics of hard ellipsoids across different aspect ratios and densities.

Findings

Decoupling of translational and rotational diffusion lines.

Glass-like stretched relaxation observed at high densities and specific aspect ratios.

Stretching of orientational correlator $C_2(t)$ occurs at large and small aspect ratios.

Abstract

We study the dynamics of monodisperse hard ellipsoids via a new event-driven molecular dynamics algorithm as a function of volume fraction $\phi$ and aspect ratio $X_0$. We evaluate the translational $D_{trans}$ and the rotational $D_{rot}$ diffusion coefficient and the associated isodiffusivity lines in the $\phi-X_0$ plane. We observe a decoupling of the translational and rotational dynamics which generates an almost perpendicular crossing of the $D_{trans}$ and $D_{rot}$ isodiffusivity lines. While the self intermediate scattering function exhibits stretched relaxation, i.e. glassy dynamics, only for large $\phi$ and $X_0 \approx 1$, the second order orientational correlator $C_2(t)$ shows stretching only for large and small $X_0$ values. We discuss these findings in the context of a possible pre-nematic order driven glass transition.