Ab initiocalculation ofH+He+charge-transfer cross sections for plasma physics

Abstract

The charge transfer in low energy (0.25 to 150 eV/amu) H(nl) + He + (1s) collisions is investigated using a quasi-molecular approach for the n = 2, 3 as well as the first two n = 4 singlet states. The diabatic potential energy curves of the HeH + molecular ion are obtained from the adiabatic potential energy curves and the non-adiabatic radial coupling matrix elements using a two-by-two diabatization method, and a time-dependent wave-packet approach is used to calculate the stateto-state cross sections. We find a strong dependence of the charge transfer cross section in the principal and orbital quantum numbers n and l of the initial or final state. We estimate the effect of the non-adiabatic rotational couplings, which is found to be important even at energies below 1 eV/amu. However, the effect is small on the total cross sections at energies below 10 eV/amu. We observe that to calculate charge transfer cross sections in a n manifold, it is only necessary to include states with n ′ ≤ n, and we discuss the limitations of our approach as the number of states increases.

Ab initiocalculation of the 66 low-lying electronic states of HeH+: adiabatic and diabatic representations

“…The radial couplings allow us to switch to the diabatic representation which is used to treat dynamical processes involving the ion. This material has been used to calculate the cross section of the photodissociation of the ion (Sodoga et al 2009) and the cross sections for the charge transfer processes He + (1s) + H(n ) −→ He(1sn 1,3 L) + H + at low energy (Loreau et al 2010). Table A2.…”

Characterization of the MgO2+dication in the gas phase: electronic states, spectroscopy and atmospheric implications

“…The collision matrix elements are extracted from wave packets by the flux method with a complex absorbing potential. 39,41 A priori, semi-classical approaches are only valid for incident energies greater than a few eV amu…”

Isotope effect in charge-transfer collisions of H with He+

“…In a recent work [2], the charge-transfer reaction between excited (n = 2,3) hydrogen and He + (1s) in the energy range 0.25 − 150 eV/amu was studied using a fully quantal approach. This reaction is particularly important in the plasma edge region, as it modifies the population of the excited states of He, which are used to determine various plasma parameters [3].…”