DENSITY EXPANSION OF FREQUENCY DEPENDENT TRANSPORT COEFFICIENTS - APPLICATION TO SPIN-ROTATIONAL INTERACTION AND OTHER RELAXATION PROCESSES

The binary collision expansion technique is utilized to obtain low-density expressions for frequency dependent transport coefficients. In particular, the Laplace transform of a correlation function expressed in terms of the dynamical variable of the internal coordinates of polyatomic molecules interacting with angular dependent forces as well as with central forces is obtained. An application to the calculation of the spinlattice relaxation time due to the spin-rotational interaction for diatomic molecules is treated in detail.