Effective potential method for active particles

ABSTRACT

We investigate the steady-state properties of an active fluid modelled as an assembly of soft repulsive spheres subjected to Gaussian coloured noise. Such a noise captures one of the salient aspects of active particles, namely the persistence of their motion and determines a variety of novel features with respect to familiar passive fluids. We show that within the so-called multidimensional unified coloured noise approximation, recently introduced in the field of active matter, the model can be treated by methods similar to those employed in the study of standard molecular fluids. The system shows a tendency of the particles to aggregate even in the presence of purely repulsive forces because the combined action of coloured noise and interactions enhances the effective friction between nearby particles. We also discuss whether an effective two-body potential approach, which would allow to employ methods similar to those of density functional theory, is appropriate. The limits of such an approximation are discussed.

KEYWORDS:

• Active matter
• non-equilibrium statistical mechanics
• fluid structure of non-conventional fluids

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Claudio Maggi was supported by the European Research Council under the European Union's Seventh Framework programme [FP7/2007-2013], [ERC grant agreement number 307940]; Matteo Paoluzzi was supported by a grant [NSF-DMR-1305184].