INVERSION SPLITTING IN THE T-CIRCLE-TIMES-T(2) JAHN-TELLER SYSTEM - TUNNELING OR HOPPING

The splitting between the two lowest vibronic states in the T x t2 Jahn-Teller system is calculated using two approximations. The first is analytical and is based on an adiabatic one-sheet WKB approximation in which the splitting is due exclusively to tunnelling. The second method is numerical and uses cubic states appropriate to very strong coupling which have been derived previously by a transformation method. The latter calculation is in direct contrast to other numerical methods which use states appropriate to the weak-coupling limit. The second calculation includes both tunnelling and 'hopping' (non-adiabatic mixing processes). Thus, by subtraction of the results from the two methods, the contributions of tunnelling and 'hopping' to the inversion splitting can be obtained. The results obtained are analysed in full and compared to other published work.