PARITY DOUBLING IN OPEN-SHELL VANDERWAALS COMPLEXES

In open-shell van der Waals complexes containing 2-PI diatomic molecules, the splitting between states with the same angular momentum quantum numbers but different parity is sensitively dependent on the intermolecular potential. The splitting for states with angular momentum projection quantum number P= +/- 1/2 has been investigated previously by Green and Lester, and shown to arise in third-order perturbation theory. We use the same model to calculate the splitting for states with P= +/- 3/2, which arises in fifth order. A formula previously used to estimate the ratio of the parity splittings in P= +/- 1/2 and +/- 3/2 states (Ohshima et al.) is shown to be incomplete, casting doubt on the resulting claim of compatibility between the measurements of these two splittings.