Common trajectory methods for the calculation of differential cross sections for inelastic transitions in atom(ion)-atom collisions. II. Application to proton-hydrogen scattering

Ionization and Single and Double Electron Capture in Proton-Ar Collisions

Total cross sections for formation of H and H^-, and electron production, in H⁺ + Ar collisions have been calculated at energies between 100 eV and 200 keV by employing two methods: for E < 10 keV, a semiclassical treatment with an expansion in a basis of electronic wave functions of the ArH⁺ quasimolecule and, for E > 10 keV, the switching-classical-trajectory-Monte Carlo method (s-CTMC). The semiclassical calculation involves transitions to molecular autoionizing states, calculated by applying a block-diagonalization technique. The s-CTMC method is adept to treat two-electron processes and yields total cross sections for H^- formation in reasonably good agreement with the experimental data. Cross sections for electron- and H-production processes, which are dominated by one-electron transitions, are in good agreement with the experimental data.

Proton hydrogen close-capture collision spectroscopy

The proton-hydrogen-atom collision is described in terms of an impact parameter perturbed-stationary-states treatment. Spurious long-range couplings are avoided and Galilean invariance is enforced by the inclusion of momentum translation factors which are determined variationally by using an Euler-Lagrange formalism. The correct physical behaviour is obtained in both the separated-atoms and united-atoms limit. The effective electronic translational kinetic energy, averaged over all internuclear separations is shown to have less influence on the phase of the close-capture probability than has hitherto been thought the case. The locations of all seven turning points in the curve of capture probability against energy, for a scattering angle of 3°, are in excellent agreement with experiment and compare more than favourably with previous extremely elaborate calculations. The adiabatic representation is thus shown to be remarkably adaptable even at energies as high as 25 keV.

Proton-hydrogen collisions: Differential and total cross sections for H(2s) and H(2p) production in the 1—7 keV range

A multistate molecular approach to the proton—hydrogen collision is formulated in terms of an impact parameter perturbed stationary-states approximation. Spurious long range couplings are avoided and Galilean invariance is enforced by the inclusion of momentum translation factors which are determined variationally within an Euler-Lagrange formalism (Crothers & Hughes 1978). Well defined radial and rotational coupling matrix elements are employed in the 1-7 keV impact energy range in a six-state (lso g , 2po u , 2pπ u , 3po u , 3pπ g , 4fo u ) calculation of elastic and inelastic differential scattering cross sections, charge exchange probabilities and both direct and exchange H (2p) production total cross sections. They are also employed in the same energy range in a ten-state (1so g , 2po u , 3dπ g , 2pπ u , 2so g , 3po u , 3do g , 4fo u , 4dπ g , 3pπ u ) calculation of both direct and exchange H (2s) production total cross sections. The results are in excellent accord with experimental data and show considerable improvement on previous molecular calculations. This success is attributed to the inclusion of both momentum translation factors and radial coupling matrix elements.