Charge exchange with multiply charged ions at low energies: application to the N3+/H and C4+/H systems

The cross sections for charge exchange in N 3 /H and C 4+ /H collisions are computed using a molecular treatment for energies in the range 0.01 to 100 eV. The potential surfaces of all molecular states which interact via avoided crossings, either directly or indirectly, with the entry channel have been calculated using a model potential method. Radial-coupling matrix elements between all interacting states of the same symmetry have been determined with precision. These are subsequently used in a fully quantum mechanical treatment of the collision dynamics. Explicit introduction of translation factors is avoided by imposing the boundary conditions on a sphere of finite radius R 0 . In the interaction region, the scattering equations take the simple PSS form with the radial-coupling matrix elements computed with respect to the origin of electronic coordinates at the centre of mass of the nuclei. With any other choice of origin, the PSS equations must be modified accordingly. The influence of rotational coupling is investigated for the C 4+ /H system. It is found to be unimportant.