Ab initio calculations of the spin–orbit splitting in the C̃ state of CF4+ including the dynamical Jahn-Teller effect

Abstract

Detailed ab initio calculations on the lowest vibrational state of the electronic C̃ 2T2 manifold of CF4+ show a small Jahn-Teller effect in all asymmetric modes. This results in only small distortions from tetrahedral symmetry, but due to strong coupling between electronic and nuclear motions (dynamical Jahn-Teller effect), the spin–orbit splitting is reduced by an order of magnitude. This answers the outstanding question on the large differences between the results of electronic structure calculations and measurements on spin-orbit splittings in XY4 molecules or molecular ions [R. N. Dixon and R. P. Tuckett, Chem. Phys. Lett. 140, 553 (1987); J. F. M. Aarts and J. H. Callomon, Mol. Phys. 81, 1383 (1994)]. Complete agreement with experiment is however not reached because the dynamical Jahn-Teller effect is very sensitive to small errors in the potential energy surface.