The effect of cooperative Jahn–Teller interactions onC60− anions

Abstract

Singly charged buckminsterfullerene anions,C60−, are subject to a strong intramolecular Jahn–Teller (JT) effect. When such ions interact with otherC60−ions in a solid through a cooperative JT effect, they will be subject to anadditional interaction. There are a number of different mechanisms thatcan cause this interaction. However, in the molecular field approximation,all can be modelled phenomenologically in terms of a symmetry-loweringinteraction written in terms of a linear combination of electronic operators for theh modes involved in the intramolecular JT effect. We will consider the combined effect of thisdistortion and the intramolecular JT effect. We will analyse the lowest adiabatic potentialenergy surface, and calculate the energies of the resultant vibronic states. The resultsare shown to have a complicated dependence on the particular combination ofh modes chosen, and the energies of the resultant vibronic states cannot easily be deducedfrom the form of the potential alone.