Vibronic coupling effects on the structure and spectroscopy of neutral and charged TiO2 clusters

► Vibronic coupling between non-degenerate states responsible for lower symmetry geometries in neutral and charged TiO2 clusters. ► CASSCF used to determine pseudo-Jahn-Teller couplings. ► Spurious symmetry breaking with different DFT functionals. ► B3LYP performs reasonably well, but care must be taken when studying charged TiO2 radicals with DFT.