Quantum mechanical calculation of ejected electron spectra for ion–atom collisions

Abstract. We present a quantum mechanical method for calculating the ejected electron probability distribution in ion–atom collisions. The time-dependent Schrödinger equation, formulated with a classical straight-line trajectory for the internuclear motion, is integrated directly on a two-centre momentum space grid. The time-dependent wavefunction at large internuclear separation is analysed to extract the ejected momentum distribution as well as excitation and charge transfer amplitudes. Calculations have been performed at collision velocities of 1, 2 and 5 au for proton and antiproton collisions with atomic hydrogen, at a few impact parameters. Excitation and charge transfer probabilities are also calculated to check against results obtained from the close-coupling method. The ejected electron momentum distributions are shown. 1