The role of the protein in light-driven biological functions: a quantum chemical view

Light-sensing proteins are responsible of a broad range of functions in biological systems, including vision, light-harvesting, photoprotection and many others. In many cases, the initial light-absorption is not localized on a single molecular unit but involves many interacting chromophores leading to a new type of delocalized excitations, the excitons. Understanding the role played by the embedding protein in controlling the formation and evolution of excitons is essential to reveal the mechanisms underlying the light-driven function. In this talk, we show that multiscale approaches based on the combination of quantum chemistry and classical models can represent a very effective strategy. Examples of application to light-harvesting pigment-protein complexes will be presented showing the importance of the coupling between static and dynamic effects due to the embedding protein.