First-principle approach to strongly coupled light-matter systems

This talk develops a first-principles description of interacting electrons, nuclei and electromagnetic fields by extending density-functional theory to quantum electrodynamics. It introduces electron–photon exchange-correlation functionals and photon many-body dispersion, a generalization of molecular dispersion methods that treats electronic and photonic degrees of freedom together. Applications examine anisotropic coupling, effects beyond single photons and cavity-modified van der Waals forces. The approach aims to retain these strong-coupling effects while remaining efficient enough to simulate large, complex systems inside optical cavities.