Description
Collisions between ions and atoms are found in a wide range of environments, including planetary atmospheres, fusion plasmas, and hadron therapy for cancer treatment. To model and analyse these environments, accurate cross sections are required for a range of atomic processes, including ionisation and excitation. Calculating these cross sections is particularly challenging for collisions with multi-electron atoms, as the electronic wave functions are not known analytically.
The convergent close-coupling (CCC) method for collisions between positrons and light atoms combines wave functions generated using the multi-configurational Hartree Fock method with Laguerre-based pseudostates to model atomic processes. This method has been shown to produce accurate cross sections for a variety of targets. However, for an ionic projectile, a fully quantum-mechanical method is not practical or necessary for collision energies greater than 1 keV, where the inelastic cross sections are most significant. Instead, the semi-classical method can be used to simplify the scattering problem. We have adapted the general and scalable semi-classical scattering equation solver developed for collisions with diatomic molecules, to the general atomic structure code used for light projectiles.
As the first step, we apply our new suite of codes to the proton-oxygen system, for impact energies in the keV to MeV range. This particular collision system has applications in auroral modelling due to the prevalence of atomic oxygen in the upper atmosphere, and as a molecular constituent through independent-atom approaches. Previous calculations approximated the field generated by the many electrons in the target using model potentials. However, the present method provides a substantially more accurate description of the oxygen atom's electronic structure and therefore a more detailed depiction of the underlying physics.
| I am the presenting author | Yes |
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