A CRITICAL ANALYSIS OF THE 2-DIMENSIONAL ATOM ELLIPSOID MODEL TO STUDY ROTATIONAL COLLISIONS

The two-dimensional (2D) hard ellipsoid model is criticized and the ca lculations are compared with the 2D classical trajectory results. The scattering angle theta and the final j for a set of initial conditions (alpha and b) have been analyzed and it was concluded that the contri bution of partial derivative j/partial derivative alpha is the leading term in the Jacobian function. Moreover, the rainbow trajectory calcu lated by the hard ellipsoid model turned out to be highly accurate for low scattering angles and semi-quantitative for the maximum rotationa l rainbow. For the latter, a relative error of about 10% has been foun d compared with classical trajectory results. Finally, an inversion pr ocedure based on such a model has also been re-analyzed and better inf ormation on the anisotropy of the interaction potential was found usin g an exact equation rather than an approximate formula for the hard el lipsoid model.