Abstract
The l‐average CS and IOS approximations are extended to treat fine structure transitions in 2P atom–1S atom scattering. Calculations of degeneracy averaged probabilities and differential cross sections for Na(2P)+He(1S) collisions in the CS and IOS methods agree well with the CC results. The present nonunitarized form of the CS approximation fails to properly predict all of the jmjm′ sections and in particular leads to a selection rule forbidding jmjm transitions for j=half‐odd integer values.