Fully relativistic convergent close-coupling method

Abstract

The calculation of accurate excitation and ionization cross sections for electron collisions with atoms and ions plays a fundamental role in atomic and molecular physics, laser physics, x-ray spectroscopy, plasma physics and chemistry. Within the veil of plasma physics lie important research areas affiliated with the lighting industry, nuclear fusion, and astrophysics. For high energy projectiles or targets with a large atomic number it is presently understood that a scattering formalism based on the Dirac equation is required to incorporate relativistic effects. This thesis reports on the development of the relativistic convergent close-coupling (RCCC) method and highlights the following three main accomplishments:1. The inclusion of the Breit interaction, a relativistic correction to the coulomb potential, in the RCCC method. This led to calculations that resolved a discrepancy between theory and experiment for the polarization of x-rays emitted by highly charged hydrogenlike ions excited by electron impact. X-rays emitted from plasmas can be used as a diagnostic tool. The RCCC results were published in Phys. Rev. A, 80(5):052708, 2009.2. The extension of the RCCC method to accommodate two electron and quasi-two electron targets. The method was applied to electron scattering from mercury. Accurate plasma physics modeling of mercury based fluorescent lamps requires detailed information on a large number of electron impact excitation cross sections involving transitions between various states. The RCCC results were published in Phys. Rev. A, 82(2):022713, 2010.3. The third accomplishment outlined in this thesis is the restructuring of the RCCC computer code (approximately 40000 lines of Fortran) to utilize a hybrid OpenMP-MPI parallelization scheme which now enables the RCCC code to run on the recently commissioned 11900 cpu supercomputer at the National Computational Infrastructure Facility in Canberra.The work presented in this thesis has resulted in international collaborations with both experimentalists and other theorists in the field of relativistic electron scattering. For example, the work on the Breit interaction has led to a collaboration with experimentalists at the GSI Helmholtz Centre for Heavy Ion Research in Germany, and total ionization cross sections for highly charged ions generated with the RCCC method are useful for plasma modelers in the USA.