Convergent close-coupling approach to light and heavy projectile scattering on atomic and molecular hydrogen

Abstract

The atomic hydrogen target has played a pivotal role in the development of quantum collision theory. The key complexities of computationally managing the countably infinite discrete states and the uncountably infinite continuum were solved by using atomic hydrogen as the prototype atomic target. In the case of positron or proton scattering the extra complexity of charge exchange was also solved using the atomic hydrogen target. Most recently, molecular hydrogen has been used successfully as a prototype molecule for developing the corresponding scattering theory. We concentrate on the convergent close-coupling computational approach to light projectiles, such as electrons and positrons, and heavy projectiles, such as protons and antiprotons, scattering on atomic and molecular hydrogen.

Electron capture, ionization and excitation cross sections for keV collisions between fully stripped ions and atomic hydrogen in ground and excited states

“…For H + impact, the differences are up to 15% at the maximum of the cross sections (50 keV) and are just a few % for the other collision energies. Note that our ionization cross sections for H + impact agree well with the recent theoretical results reported in [16]: the differences between our data and that in [16] are only a few % at high collision energies and less than 20 % for the lower energy range of this latter work. For He 2+ , the agreement between the present results and the experimental data [14] and the various cross sections reported in [17] are within 15%.…”

A statistical description of scattering at the quantum level

“…via correlations and collective effects which require treatments of electronic dynamics beyond the single active electron approach. Indeed these effects are known to be fundamental in atomic and molecular physics and pose a significant challenge to theoretical approaches 1 – 3 .…”

“…The description of their energy dependence using quantum, classical and semi-classical approaches remains challenging, even in the case of simple atomic targets and structureless projectiles (e.g. 1 – 3 ). Difficulties increase further in the case of higher-order processes (e.g.…”

Collision processes using effective potentials

“…In particular, we examine several collisional processes involving a single electron transition: photoionisation, excitation, ionisation and electron capture. A wide variety of ab initio methods have been implemented to compute scattering cross sections for atomic targets, from the early implementations of the first Born approximation (FBA) [6,7], to more sophisticated fully quantum mechanical methods, e.g., [8,9,10,11]. Whether for atoms or molecules, we shall present cross sections and compare with some experimental data.…”