Quadratic Jahn-Teller effect of fullerene anions

Abstract

The quadratic Jahn-Teller effect of C n− 60 (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 to be about 2 meV, which is much smaller than the Jahn-Teller stabilization energy (≈ 50 meV). Because of the selection rule and the vibronic reduction, the quadratic coupling slightly modifies the vibronic states of C60 anions. Particularly, in the case of C 3− 60 , 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 n− 60 is of pseudorotational type. II. QUADRATIC JAHN-TELLER MODEL FOR C60 ANIONS A. bielectronic and vibronic interactionsThe neutral fullerene C 60 (I h symmetry) has triply degenerate t 1u lowest unoccupied molecular orbitals (LUMO). The LUMO levels are well separated from the other molecular orbital levels, therefore, the t 1u shell model describes adequately the low-energy electronic structure of C n− 60 anions (n = 1-5). The model Hamil-arXiv:1805.08246v2 [cond-mat.str-el]

Dynamical Jahn‐Teller effect in the first excited

“…Vibronic coupling parameters were derived by fitting model potential to the gradients of NLUMO levels of neutral C 60 calculated with B3LYP functional taken from Reference . The calculations with CAM‐B3LYP were done with Gaussian 16, with basis set 6‐311G(d).…”

“… Note : The data for LUMOs with B3LYP are obtained from Reference with frequencies obtained from Reference .…”

“…Since the molecular nature strongly remains in these materials, thorough understanding of the JT effect of C 60 anions is crucial. Although JT effect, including dynamic one, of C 60 anions has been intensively investigated, it is only past few years that the actual situation of the ground electronic states of molecule (n = 1‐5) has been established with accurate vibronic coupling parameters …”

Dynamical Jahn-Teller effect in the first excited C$_{60}^-$

“…The vibronic coupling parameters are derived by fitting the model potential to the gradients of NLUMO levels calculated in Ref. 33. The calculations were done using DFT calculations with hybrid B3LYP functional, because, indicated by the previous studies, B3LYP could give closer parameters to the experimental data 34,68 , and has a good agreement wit GW approximation calculations 71 .…”

“…In order to comprehend thoroughly the role of the building brick, many properties of negatively charged C 60 should be understood clearly, especially about JT effect involved properties. Though JT effect, including dynamic JT effect, of C 60 anions have been intensively investigated , it is only last years that the actual situation in the ground electronic states of C n− 60 molecule (n = 1 − 5) has been established with accurate coupling parameters, which showed the importance of dynamic JT effect 32,33 .…”