Binary friction tensor for Brownian particles : overcoming spurious   finite-size effects
  Starting from a careful analysis of the coupled Langevin equations for two interacting Brownian particles, we derive a method for extracting the binary friction tensor from the correlation function matrix of the instantaneous forces exerted by the bath particles on the fixed Brownian particles, and from the relaxation of the total momentum of the bath in a {\it finite} system. The general methodology, which circumvents the pitfalls associated with the inversion of the thermodynamic and long time limits, is applied to the case of two Brownian hard spheres in a bath of light spheres. 
Lyd\'eric Bocquet (1), Jean-Pierre Hansen (1) and Jaroslaw Piasecki   (2) ((1)ENS Lyon France and (2) Institute of Theoretic...