Strong-coupling semiclassical methods: phase-corrected average approximation for atom--atom collisions

A method is presented for improving the phase of the semiclassical radial functions obtained from the average approximation. It yields improved phases for problems possessing localized regions of strong coupling, for example, in curve-crossing problems. For problems without such regions, the method yields essentially the same results as the average approximation. Results are presented for atomic-scattering situations in both close-coupling and distorted-wave theory.