Forced rotational diffusion of linear molecules. Nonlinear aspects

Abstract

The decay of fluctuations in orientation of a system of linear molecules interacting via electrostatic forces is determined by solution of the forced diffusion equation in its nonlinear form. The results consist of series expansions of the time dependent coefficients of the expansion of the distribution function for orientation in spherical harmonics. Separate expansions in terms of the scale of fluctuations and in terms of the magnitude of the dipole–dipole forces are given. The nonlinearity causes the appearance of terms in the expression for the fluctuation decays which evolve on a time scale shorter than that of the free diffusion.