Memory effects in the motion of nonspherical Brownian particles

A system of nonlinear generalized Langevin equations is stated to describe the motion of noninteracting nonspherical Brownian particles. The coupling of translational and rotational degrees of freedom is taken into account via anisotropic translational and rotational friction coefficients, a Magnus force term and a systematic torque. A kinetic equation is derived with time- dependent coefficient functions, which are explicitly calculated for the one-mode case. As an example the frequency dependence of the coefficient of flow birefringence is discussed.