ELECTRON-CAPTURE AND EXCITATION IN PROTON-NA-20 COLLISIONS AT LOW VELOCITIES

We present a many-electron theoretical study of electron capture and e xcitation in collisions of H+ with Nato clusters for impact energies 4 0-500 eV. The collision is treated semiclassically using the independe nt electron model, and the cluster is described in the framework of th e Kohn-Sham formalism with a local-density approximation which include s exchange, correlation, and a self-interaction correction. We have fo und that capture cross sections are similar to(2-5)x10(-14) cm(2) and dominate in the above energy range. In contrast with ion-atom collisio ns, excitation cross sections are comparable to the former, and multip le processes such as capture excitation cannot be neglected at low vel ocities. From the analysis of the vacancies originated in the collisio n, we have evaluated the energy deposited in the cluster, which is an essential parameter in the study of cluster fragmentation.