A study of the quadratic p2 ⊗ h Jahn–Teller system

A Jahn–Teller (JT) coupling model is developed for the p2 ⊗ h JT system as a possible model for the doubly charged C 60 2 - dianion. The model described specifically includes second-order electron–vibration interactions which generate minima in the potential energy surface of either D5d or D3d symmetry depending on the strength of the JT coupling. Expressions are derived for the energies of these minima and linear combinations of the associated states are formulated that represent the vibronic states of the ion at intermediate coupling strengths. The energies of these symmetry-adapted states are given graphically and consideration is also given to the Coulombic interactions between the two electrons. Numerical application is made to the C 60 2 - ion using parameters taken from the literature.