# Frictional Active Brownian Particles

## TL;DR

This study uses numerical simulations to show that frictional forces significantly influence the behavior and phase separation of active Brownian particles, altering their phase diagram and stability.

## Contribution

It reveals how frictional forces modify the dynamics and phase behavior of active Brownian particles, a novel insight into their collective behavior.

## Key findings

- Friction increases angular diffusivity of particles.
- Friction prevents collision resolution by sliding.
- Frictional systems become unstable regardless of volume fraction.

## Abstract

Frictional forces affect the rheology of hard-sphere colloids, at high shear rate. Here we demonstrate, via numerical simulations, that they also affect the dynamics of active Brownian particles, and their motility induced phase separation. Frictional forces increase the angular diffusivity of the particles, in the dilute phase, and prevent colliding particles from resolving their collision by sliding one past to the other. This leads to qualitatively changes of motility-induced phase diagram in the volume-fraction motility plane. While frictionless systems become unstable towards phase separation as the motility increases only if their volume fraction overcomes a threshold, frictional system become unstable regardless of their volume fraction. These results suggest the possibility of controlling the motility induced phase diagram by tuning the roughness of the particles.