The Quantum Chemistry unit focuses on the computation of the structure and dynamics of atomic and molecular species relevant in various fields such as spectroscopy, atmospheric chemistry, astrophysics or astrochemistry. We perform accurate computations of molecular spectra, which can be compared to experimental measurements and astrophysics data. Our focus is on the rovibronic structure of molecules of astrophysical interest. To achieve this, we have developed original methods for ab initio calculations and fitting procedures to construct multidimensional potential energy surfaces. We treat highly excited electronic states in small systems, as those states participate in a wide range of reactions, including charge transfer, molecular photodissociation, ion-pair production and neutralization and isomerization. These reactions are important in both astrophysical environments and plasma physics.