Motility-Induced Inter-Particle Correlations and Mass Transport

Amongst the various theoretical approaches towards dynamics and phase behaviour of suspensions of active Brownian particles (ABPs), no attempt has been made to specify motility-induced inter-particle correlations, starting from microscopic considerations. In this presentation, a particle-based derivation of explicit expressions for the pair-correlation function for ABPs for small and large swimming velocities and low concentrations is derived. This allows to obtain a generalization of Fick’s law for the colloid concentration that includes self-propulsion. It will be shown that there is a concentration-gradient induced preferred swimming direction, due to inter-particle correlations, which tends to stabilize the system against spinodal phase separation. J.K.G. Dhont, G.W. Park, W.J. Briels, Soft Matter 17 (2021) 561