Stochastic equations of motion for nonspherical particles

The dynamics of a classical system consisting of noninteracting linear molecules, which are described by rigid rotors, and a heat bath of point particles is studied from a microscopic point of view. Kinetic equations are derived in the weak coupling- and singular coupling limit. They are approximated by Markovian equations eliminating the fastly oscillating variables. The results are discussed by means of the corresponding stochastic equations of motion, from which the statistical properties of the stochastic forces and the coupling between the translational and the rotational motion are inferred.