Phase co-existence in bidimensional passive and active dumbbell systems

TL;DR

This paper investigates phase coexistence in two-dimensional passive and active dumbbell systems, revealing macroscopic coexistence of ordered and disordered regions over a range of densities, with no abrupt changes upon increasing activity.

Contribution

It demonstrates the persistence of phase coexistence in active dumbbell systems and compares it to passive systems, highlighting the continuous transition with activity.

Findings

Macroscopic coexistence of hexatic and liquid/gas phases in active systems.

Finite coexistence interval persists from passive to active regimes.

No discontinuous behavior observed with increasing activity.

Abstract

We demonstrate that there is macroscopic co-existence between regions with hexatic order and regions in the liquid/gas phase over a finite interval of packing fractions in active dumbbell systems with repulsive power-law interactions in two dimensions. In the passive limit this interval remains finite, similarly to what has been found in bidimensional systems of hard and soft disks. We did not find discontinuous behaviour upon increasing activity from the passive limit.