Two-dimensional atom ellipsoid model for analysing He-Li2[(A)1Σu+] rotational collisions with multiple impacts

A classical two-dimensional atom ellipsoid model is used to analyse the collisions in the rotational excitation of the He and Li-2 interaction. Several collision energies are used to investigate how the anisotropy can affect the dynamical parameters such as the scattering angle. Several impacts are found at the same trajectory by using the ellipsoid model, which does not take into account attractive forces. The total state-to-state rotational cross sections calculated with this model are compared with previous calculations (L. K. Cooper, A. J. McCaffery and S. D. Bosanac, J. Phys. B, 1991, 24, 811) based on classical trajectory calculations. Very satisfactory agreement is found when several impacts at the same trajectory are considered.