Molecular dynamics simulations were made of ion-beam mixing during the 100eV Ar and Xe ion bombardment of a (100) Cu crystal. The Gibson-II potential was splined to a Morse potential or to a tight-binding many-body potential. Calculations were performed at 0K for up to 4ps. The relocation function, the mean drift velocity of recoils and the mixing coefficient, as well as the mean square displacement, were calculated from the results of the molecular dynamics simulations. The problem of marker degradation was solved numerically by using the integrodifferential mixing equation and a molecular dynamics-simulated function of the atomic jumps. The kinetics of the defect distributions (adatoms, vacancies. interstitials), the mean square displacements of atoms in the cascade and the numbers of atomic jumps of an atom from one Wigner-Seitz cell to another were considered. It was found that Ar ions created about twice as many vacancies in the first layer, and adatoms on the surface, as did Xe ions. On the other hand, the number of interstitials (which occurred only in the bulk of the crystal) was slightly larger for Xe bombardment. A negative value of the mean drift velocity in the first layer, for Ar bombardment, was connected with a large number of atomic jumps from the first layer and into adatom positions. A slower decrease of the mixing coefficient with depth, for Xe ion bombardment, was related to a greater penetration depth of Xe ions into the crystal and to a smaller back-scattering coefficient as compared to Ar. The need to take account of the thermal stage of cascades in low-energy ion-beam mixing was demonstrated.

G.V.Kornich, G.Betz, B.V.King: Nuclear Instruments and Methods in Physics Research B, 1996, 115[1-4], 461-7