Density functional theory study of the multimode Jahn-Teller problem in the open-shell corannulenes and coronenes

Analysis of the multimode Jahn-Teller (JT) distortion in anions and cations of corannulene and coronene is presented, combining multideterminantal-DFT (MD-DFT) and Intrinsic Distortion Path (IDP) methods. The JT distortion is derived from the sum of contributions of all possible JT active normal modes. The C-C stretching modes play the most important role in the stabilization of the systems, in all investigated species, pushing the nuclei toward the minima on the potential energy surface. The further inspection of the IDP revealed that the relaxation of the geometry arrives in the final part of the path and is encountered by the softest vibrational modes. The same trend was observed in cyclopentadienyl radical, benzene anion, benzene cation and fullerene ions. This gives microscopic origin into the mechanism of the distortion and provides general behavior of the JT effect in these similar molecules. Moreover, MD-DFT and IDP, as fast and fully non-empirical approaches, can be considered as a reliable tool for better understanding of the JT effect