Stochastic dynamics of collective modes for Brownian dipoles
  The individual motion of a colloidal particle is described by an overdamped Langevin equation. When rotational degrees of freedom are relevant, these are described by a corresponding Langevin process. Our purpose is to show that the microscopic local density of colloids, in terms of a space and rotation state, also evolves according to a Langevin equation. The latter can then be used as the starting point of a variety of approaches, ranging from dynamical density functional theory to mode-coupling approximations. 
Leticia F. Cugliandolo and Pierre-Michel D\'ejardin and Gustavo S.   Lozano and Fr\'ed\'eric van Wijland
cond-mat.stat-mech cond-mat.soft