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Report for Theoretical Spectroscopy Lectures 2024

The aim of the school was to give a comprehensive introduction to the theoretical and practical aspects of the electronic excitations  that are probed by experimental techniques such as optical  absorption, EELS and photoemission (direct or inverse). From a theoretical perspective, excitations and excited state properties are out of the reach of density-functional theory (DFT), which is a ground-state theory. Over the past three decades, alternative ab-initio theories and frameworks capable of describing electronic excitations and spectroscopy, have gained popularity including time-dependent density-functional theory (TDDFT) and many-body perturbation theory (MBPT) or Green’s function theory (GW approximation and Bethe-Salpeter equation BSE). In fact, computational solutions and codes have been developed to implement these theories and to provide tools to calculate excited state properties. The present school focused on these points, covering theoretical, practical, and also numerical aspects of TDDFT and MBPT, non-linear response and real-time spectroscopies. Additionally, the school provided valuable insights from an experimental perspective on spectroscopies and magnetic excitations, rarely covered in similar events. Finally, a large part of the school was devoted to getting familiar with the codes that implement such theories (ABINIT, 2Light, Lumen, DP, and EXC). Continue reading Report for Theoretical Spectroscopy Lectures 2024