Abstract
Close-coupling nonexchange calculations are performed for the processes H(1s)+H(1s) to H(2s or 2p)+H. In addition nonclose-coupling exchange calculations are carried out. For both processes it is concluded that the inclusion of exchange effects is essential at lower impact energies and that exchange increases the cross sections over the non-exchange results. Also for both processes the indications are that the first Born approximation may be valid for impact energies greater than about 150 keV.