On the use of body-fixed coordinates in classical scattering calculations: Planar trajectory approximation for rotational excitation

The use of body-fixed coordinates in classical scattering calculations is investigated. It is shown that while the exact body-fixed equations are cumbersome, they are amenable to the introduction of simplifying approximations. One such approximation, the assumption of planar trajectories, is investigated in detail and is shown to yield accurate cross sections for rotationally inelastic Ar–N2 scattering.