Jahn-Teller induced microwave spectra of the C₇₀ ⁺ fullerene cation.

The C 70 molecule is apolar. Upon ionization Jahn-Teller effects occur that distort the D 5h neutral symmetry to C s . This point group is polar thus ionization induces a permanent electric dipole moment in C 70 . The goal of the present calculations is to compute the equilibrium geometry and dipole moment of the C 70 + cation by various DFT methods and to simulate microwave spectra. Using the Gaussian16 quantum chemistry program rotational constants, Cartesian dipole moment components, and the resultant dipole, as well as the Jahn-Teller stabilization energy and the HOMO-LUMO gaps were obtained. The microwave rotational spectra at gas phase temperatures 2.73 K and 10K were simulated using the Pgopher software. These spectra may serve as starting point for laboratory microwave measurements and as screening guide in radio astronomical searches. The static Jahn-Teller effect in C 70 + is the consequence of the mixing of the two highest ground state occupied orbitals, thus it is a pseudo Jahn-Teller effect.