Convergent J-matrix calculation of electron-hydrogen resonances

It is shown that electron-hydrogen resonances can be evaluated to any required accuracy using the J-matrix method. Resonance structures in 2s and 2p electron-hydrogen excitation cross sections are calculated. It is found that the present J-matrix results are in very good agreement with the calculations of Callaway and therefore with the absolute experimental data of Williams. The R-matrix calculations of Fon et al are found to overestimate the correct absolute values of 2s and 2p cross sections. (author)