THE SEMICLASSICAL CLOSE-COUPLING DESCRIPTION OF ATOMIC-COLLISIONS - RECENT DEVELOPMENTS AND RESULTS

Developments in the semiclassical close-coupling description of atomic collisions, in an energy range of roughly 0.1 up to a few hundred keV per nucleon of the projectile, are reviewed with emphasis on recent progress in its application to a wide range of collision phenomena. After a qualitative discussion of the basics of the close-coupling description, we introduce the commonly used basis sets, such as sets of molecular orbitals, atomic orbitals and pseudostates, which are employed to define the truncated Hilbert space for the time evolution of the electronic wavefunction. It is shown that experimental data for the dominant and subdominant electron transition channels, for collision systems with one or two active electrons, are generally well described by the close-coupling method with moderately sized basis sets. Recent progress in studies of angular-momentum coherences in collisionally excited states illustrates the general reliability of the relative phases of scattering amplitudes from the close-coupling calculations. The limitations of the close-coupling description as well as possible new areas for future applications are also discussed.