Electronic excitations 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 twenty 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 focuses on these points, covering theoretical, practical, and also numerical aspects of TDDFT and MBPT, and codes implementing them (ABINIT, DP, EXC, 2Light, Lumen).
- Spectroscopy techniques. Connection between microscopic and macroscopic worlds.
-Density Functional Theory: basics concepts, pseudo-potentials, functionals.
-Many-body Perturbation theory: GW approximation, COHSEX, Bethe-Salpeter Equation (BSE)
-Time Dependent Density Functional Theory: basic concepts, kernels, connections with BSE.
- Out-of-equilibrium spectroscopy: harmonic generation and sytem under intense laser fields