Differential cross sections for elastic scattering, resonant charge exchange and excitation in low energy proton-hydrogen collisions

The H + -H collision is investigated using the three-state molecular expansion, which takes account of the coupling between 2p sigma and the 2p pi states of the H 2 + quasi-molecule. Differential cross sections for direct elastic scattering, resonant charge exchange and direct and exchange excitation of H(2p) have been computed for a range of incident proton energies from 150 eV to 2.84 keV and for a range of scattering angles from 0 to 10 degrees (in laboratory system). The agreement with the experimental results is excellent. The nature of non-adiabatic effects in low energy H + -H collisions is discussed in detail.