October 8, 2018 to October 12, 2018
Location: CECAM-HQ-EPFL, Lausanne.
The aim of the school was to give a deep introduction on the theoretical and practical aspects of the electronic excitations, which are probed by experimental techniques such as optical absorption, EELS and photo-emission (direct or inverse). From the theory point of view, excitations and excited state properties are out of the reach of density-functional theory (DFT), which is a ground-state theory. In the last thirty years, other ab-initio theories and frameworks, which are able to describe electronic excitations and spectroscopy, have become more and more used: 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 in order 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 reponse and real-time spectroscopies. Finally, a large part of the school was devoted to the codes implementing such theories (ABINIT, 2Light, Lumen, DP, EXC).