X-ray resonant Raman scattering Spectra simulation from first principles for Copper below the ionization threshold using high-performance computing

• Autor(a) principal: Baptista, Gonçalo Garcês Sobreira Rodrigues
• Data de Publicação: 2023
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/162829
• topic: Radiative relaxation; x-ray transition lines; photoexcitation; MCDFGME; DCS; High Performance Computing; Domínio/Área Científica::Engenharia e Tecnologia::Outras Engenharias e Tecnologias

The work performed on this thesis comes as part of the effort to further understand the highly convoluted structure present on Copper’s x-ray emission spectra, where, as with many other transition metals, a skewness can be observed on the K1 and K2 x-ray transition lines. These lines originate due to the radiative relaxation of the atom’s electronic structure post-ionization of inner shell electrons. One of the possible explanations for the observed skewness are Copper’s radiative transitions originating from its satellite states. Throughout this thesis, a study will be performed for the satellite states formed by the excitation of the inner-shell electrons, where a photoexcitation process occurs, as opposed to the ionization process that is usually considered in x-ray calculations, and all the consecutive radiative decay possibilities. Multiple atomic structure calculations will be performed using the ab initio state-ofthe- art Multiconfiguration Dirac-Fock General Matrix Elements (MCDFGME) code for different excited states configurations. The obtained results can then be used in the analysis of experimental data obtained with a High-Precision Double Crystal Spectrometer (DCS), using a synchrotron x-ray source. Due to the complexity of the calculations, the process can become substantial in terms of computational power and time. Therefore, a parallelized calculation deploying code, employing a Message Passing Interface (MPI) protocol and High Performance Computing, will be written as to be able to perform similar but more complex calculations using a supercomputer, such as the one in the University of Évora (OBLIVION).