Molecular dynamics simulation of orientational glass formation in anisotropic particle systems in three dimensions

TL;DR

This study uses molecular dynamics simulations to explore how anisotropic particles form orientational glasses in three dimensions, revealing domain formation, slow rotational dynamics, and shape memory effects.

Contribution

It introduces a simple microscopic model to simulate orientational glass formation in 3D anisotropic particle systems, highlighting impurity effects and domain structures.

Findings

Formation of rhombohedral domains during cooling.

Impurities induce medium-range orientational order.

Rotational dynamics slow down at low temperatures.

Abstract

We propose a simple microscopic model of molecular dynamics simulation to study orientational glass in three dimensions. We present simulation results for mixtures of mildly anisotropic particles and spherical impurities. We realize fcc solids without orientational order in a rotator phase. As the temperature $T$ is lowered, the disordered matrix is gradually replaced by four kinds of orientationally ordered, rhombohedral domains. Two-phase coexistence is realized in a temperature window. The impurities serve to anchor the orientations of the surrounding anisotropic particles, resulting in finely divided domains or medium long-range orientational order. We examine the rotational dynamics of the molecular orientations which is slowed down at low $T$. We predict the shape memory effect under a stretching cycle due to inter-variant transformation.