INFLUENCE OF ELECTRONIC EXCHANGE ON SINGLE AND MULTIPLE PROCESSES IN COLLISIONS BETWEEN BARE IONS AND NOBLE-GAS ATOMS

The time-dependent many-electron problem encountered in the theory of energetic ion-atom collisions can be approached systematically within an effective single-particle picture, based, e.g., on the time-depende nt density functional theory. In the present contribution we investiga te ionization and electron loss from the target for the collision syst ems p, (p) over bar, He2+ + Ne, and p + Ar in the energy range 10 keV/ amu-1 MeV/amu. The results presented are based on a static approximati on to the exchange-correlation contribution of the effective potential . The corresponding time-dependent single-particle equations are solve d with the continuum distorted-wave with eikonal initial-slate approxi mation and the basis generator method, a coupled-channel approach in t erms of structurally adapted basis functions. We demonstrate that in e ither case the results depend strongly on the explicit form of the loc al static exchange potential. An orbital-dependent analysis of electro n removal in He2+ + Ne collisions shows that the quality of the exchan ge potential is decisive for the suppression of artificial reaction ch annels.