Molecular treatment of charge transfer in He²⁺-H collisions

A multistate molecular approach to the He 2+ -H collision is applied within an impact parameter perturbed-stationary-states formulation. Spurious long-range couplings are avoided and Galilean invariance is enforced by the inclusion of electronic momentum translation factors determined variationally within an Euler-Lagrange formalism (Crothers and Todd). Well defined, symmetrised radial and rotational coupling matrix elements are employed in the 4 He 2+ impact energy range 2-25 keV in a five-state (2p sigma , 2p pi , 3d sigma , 3d pi , 2s sigma ) calculation of total and 4 He + (2s) capture cross sections. They are also used over the 0-3 degrees laboratory scattering angle range to calculate elastic and inelastic differential cross sections at a 3 He 2+ impact energy of 4.5 keV. Results for the capture probability at 1.2 degrees agree reasonably well with the experiment of Keever and Everhart (1966) over the 3 He 2+ 2-20 keV energy range and are compared with previous molecular calculations.