Near-threshold rotational excitation in electron scattering by the HCl molecule

A variation R-matrix calculation has been performed for electron scattering by the HCl molecule. Rotational non-adiabatic effects have been included using a modified frame transformation method, in which the body-frame vibronic R-matrix constructed from a variationally computed fixed-nuclei electronic R-matrix, is frame-transformed at the R-matrix boundary. In our implementation Born closure can be used effectively for the final calculation of cross sections. The validity of the first Born approximation (FBA) for different classes of rotational transitions is discussed. (author)