Quadratic Jahn-Teller effect of fullerene anions

Abstract

The quadratic Jahn-Teller effect of C${}_{60}^{n-}$ ($n=$ 1-5) is investigated from the first principles. Employing the density functional theory calculations with hybrid functional, the quadratic vibronic coupling constants of C${}_{60}^{-}$ were derived. The warping of the adiabatic potential energy surface of C${}_{60}^{-}$ by the quadratic vibronic coupling is estimated about 2 meV, which is much smaller than the Jahn-Teller stabilization energy ($\approx$ 50 meV). Because of the selection rule and the vibronic reduction, the quadratic coupling slightly modifies the vibronic states of C${}_{60}$ anions. Particularly, in the case of C${}_{60}^{3-}$, parity and symmetry selection rule significantly reduces the effect of quadratic coupling on vibronic states. The present results confirm that the low-energy vibronic dynamics of C${}_{60}^{n-}$ is of pseudorotational type.

9 pages