Many-body perturbation theory allows to systematically capture correlation effects responsible for emergent collective behaviours in an electronic system. Combining many-body perturbation theory with density-functional theory results in universal, parameter-free numerical approaches that allow one to quantitatively address spectroscopic properties of materials, given the atomic positions as the only input. Indeed, those techniques are nowadays the state-of-the-art to simulate e.g. optical absorption, electron energy loss and photoemission spectra for a broad range of materials.

Notwithstanding this success, active development of those approaches, and the associated computational tools are ongoing:

• to design strategies and efficient numerical algorithms to treat systems with a large number of degrees of freedom
• to capture relevant effects that are not yet included in state-of-the-art approaches (e.g. temperature)
• to describe other spectroscopic properties (e.g real-time, femtosecond spectroscopic techniques) and excitations

 Researcher: Myrta Grüning