Molecular theory of Langevin dynamics for active self-diffusiophoretic colloids

Abstract

Active colloidal particles that are propelled by a self-diffusiophoretic mechanism are often described by Langevin equations that are either postulated on physical grounds or derived using the methods of fluctuating hydrodynamics. While these descriptions are appropriate for colloids of micrometric and larger size, they will break down for very small active particles. A fully microscopic derivation of Langevin equations for self-diffusiophoretic particles powered by chemical reactions catalyzed asymmetrically by the colloid is given in this paper. The derivation provides microscopic expressions for the translational and rotational friction tensors, as well as reaction rate coefficients appearing in the Langevin equations. The diffusiophoretic force and torque are expressed in terms of nonequilibrium averages of fluid fields that satisfy generalized transport equations. The results provide a description of active motion on small scales where descriptions in terms of coarse grained continuum fluid equations combined with boundary conditions that account for the presence of the colloid may not be appropriate.

arXiv comment15 pages, 2 figures

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Cited by in corpus (5)

• Inertial effects on rectification and diffusion of active Brownian particles in an asymmetric channel
• Microscopic theory of a Janus motor in a non-equilibrium fluid: Surface hydrodynamics and boundary conditions
• The non-equilibrium thermodynamics of active suspensions
• The stress tensor of dilute active colloidal suspensions
• Mass-based separation of active Brownian particles in an asymmetric channel