Decoupling approximations in the quantum mechanical treatment of P-state atom collisions

Several decoupling schemes are considered, for the effective simplifications of the close coupling equations which arise in the treatment of atomic collisions involving fine structure. Calculations were performed for two models of 2P atoms colliding at thermal energy with a 1S species. From the comparison of exact and approximate results, the relative merits and limits of full or partial decoupling schemes were assessed. Possible improvements and extensions are suggested.