Low-energy electron scattering by atomic hydrogen: I. The close-coupling approximation

The results of a six-state close-coupling calculation of low-energy electron scattering by atomic hydrogen are presented. The first six hydrogen atom eigenstates are retained in the expansion of the total wave function and the resultant equations solved on a C.D.C. 6600 computer. Resonances are found below the n = 3 excitation threshold of atomic hydrogen and they are shown to play an important role in the excitation cross sections Q (1s-2s) and Q (1s-2p). For energies insufficient to excite these resonances it is found that the three-state close-coupling approximation gives reliable results. Finally, cross sections are given for the transitions between the n = 1 and 3 and the n = 2 and 3 levels of atomic hydrogen as well as for elastic scattering on the ground state.