Important! For registration and more information about the event please visit our website: https://www.etsfyrm2023.com/

The European Theoretical Spectroscopy Facility is a network of European research teams of outstanding international reputation. Its objective is research excellence and scientific outreach at the institutional and industrial levels, notably through the organization of international conferences and workshops. Among the many initiatives of the ETSF is the Young Researchers’ Meeting (YRM). The main focus of the ETSF is traditionally theoretical spectroscopy, which in itself is quite a broad field. As the network developed and grew, so did the Young Researchers’ Meeting, and the topics covered diversified. We plan to cover most of them by having five different oral sessions.

The first is about electronic structure methods development. To go beyond the standard Density Functional Theory, a lot of effort is put into developing new functionals to study more diverse systems, such as Koopmans-compliant functionals for finite molecules [1]. Other methods, such as the many-body GW approximation, are also widely used to compute accurate electronic structure, and are under constant improvement to study more and more complex systems, such as 2D materials [2], van der Waals heterostructures or defected crystals. 

The second session is about strongly correlated systems and magnetism. The strongly correlated systems exhibit phenomena that cannot be explained using the standard band theory. These systems include a wide class of materials, the most characteristic ones being the Mott insulators [3], geometrically frustrated pyrochlore magnets (spin ices [4]), 4f-electron systems (heavy fermions [5], Kondo insulators [6]), and unconventional superconductors (cuprates [7]). Overall, the investigation of such systems attracts a large research interest due to the related novel unusual phenomena and they constitute a great playground for the study of complicated many-body processes. The correct description of the electronic correlations requires adequate methods such as the dynamical mean field theory (DMFT) [8], slave particle approaches [9], Quantum Monte Carlo [10], and others. 

The third session is devoted to vibrational properties and transport. The standard methods to compute phonon properties include Density Functional Perturbation Theory, in which deformation potentials are computed in a perturbative way,  or frozen-phonons, in which quantities of interest are computed with finite-difference derivatives. In the case of molecules, one has to go beyond the Born-Oppenheimer approximation and treat the vibrational properties in a non-adiabatic way. One can resort to mixed quantum-classical non-adiabatic dynamics to describe finite-size systems accurately while also including the effect of the environment [11]. Coupling between electrons and phonons is crucial to describe many phenomena, among which electronic transport is a key quantity [12].

The fourth session is about optical properties and non-linear spectroscopy. A variety of optical quantities can be computed numerically, with ever increasing precision relative to experiments. Multiple software can be used such as VASP, SIESTA, yambo, Elk, Octopus and many more. Time-resolved ultrafast spectroscopy with simulation of pump-probe experiments, exciton dynamics obtained with time-dependent Bethe-Salpeter equation [13], or high-harmonic generation [14], are fields that attract a lot of attention lately.

The final session is about quantum computing. It is the specificity of the YRM 2023. As of the recent years, it has attracted huge attention. Indeed, with the new algorithms developed specifically for quantum computers, it might be possible to achieve time complexities that are not possible on classical computers. Research is starting in the field of theoretical condensed matter with interesting perspectives in sight [15,16].