Photoionization, electron-ion recombination and radiative processes of He and Ne rare gas atoms using relativistic Dirac R-matrix method

Abstract EN

The Photoionization, Electron -ion recombination and Radiative Processes of He and Ne rare gas atoms are investigated using the fully relativistic R-matrix method.

These processes are fundamental atomic processes in astrophysical plasmas.

In most existing astrophysical models these atomic data are from methods that do not sufficiently consider the level of complexity attributable to the large number of autoionizing resonances that manifest themselves in the photoionization cross-sections and, consequently, in the inverse process of (electron-ion) recombination.The Dirac Atomic R-matrix Code has been extended from low-energy electron scattering to handle bound states, photoionization and radiative recombination .In the relativistic R-matrix calculations,the sequare integrable orbitals are obtained from the multiconfiguration Dirac-Fock method by using GRASP code, where in this method, an atomic state is approximated by a linear combination of configuration state functions of the same symmetry.

The configuration state functions are antisymmetrized products of a common set of orthonormal orbitals which are optimized on the bases functions of Dirac-Coulomb Hamiltonian.This basis is used to obtain bound orbitals from which the target ions are constructed in DARC code.

Further relativistic contributions to the atomic states due to Breit interactions are added by diagonalizing the Dirac-Coulomb-Breit Hamiltonian matrix.

The dominant quantum electrodynamic contibutions have also been included as a perturbation.

Calculations have been performed on He and Ne rare gas atomic systems, where good agreement is obtained between the results in this paper with the results of others.