Frustration of freezing in a two dimensional hard-core fluid due to particle shape anisotropy

TL;DR

This study investigates how particle shape anisotropy affects the freezing transition in a two-dimensional hard-dumbbell fluid, revealing a critical length beyond which the transition may become continuous instead of abrupt.

Contribution

It demonstrates that increasing particle anisotropy in a 2D hard-dumbbell fluid alters the nature of the freezing transition, extending understanding of shape effects on phase behavior.

Findings

Dumbbell length under 15% of disk diameter leads to freezing transition.

Dumbbell length over 15% may cause the transition to become continuous.

Transition type depends on particle shape anisotropy.

Abstract

The freezing mechanism suggested for a fluid composed of hard disks [Huerta et al., Phys. Rev. E, 2006, 74, 061106] is used here to probe the fluid-to-solid transition in a hard-dumbbell fluid composed of overlapping hard disks with a variable length between disk centers. Analyzing the trends in the shape of second maximum of the radial distribution function of the planar hard-dumbbell fluid it has been found that the type of transition could be sensitive to the length of hard-dumbbell molecules. From the ${NpT}$ Monte Carlo simulations data we show that if a hard-dumbbell length does not exceed 15% of the disk diameter, the fluid-to-solid transition scenario follows the case of a hard-disk fluid, i.e., the isotropic hard-dumbbell fluid experiences freezing. However, for a hard-dumbbell length larger than 15% of disk diameter, there is evidence that fluid-to-solid transition may change to continuous transition, i.e., such an isotropic hard-dumbbell fluid will avoid freezing.