Surface Science 202 (1988) 309-319 North-Holland, Amsterdam 309 zyxwvutsrq MODEL STUDIES OF PARTICLE/ SOLID INTERACTIONS zyxwvutsrqponmlkjihgf C.-C. CHANG *, N. WINOGRAD and B.J. GARRISON * * The Pennsylvania State University, Department of Chemistty, 152 Davey Laboratory, University Park, PA 16802, USA Received 4 December 1987; accepted for publication 8 April 1988 The interaction of keV particles with surfaces has traditionally been expressed in terms of successive single binary elastic collisions. In this study, molecular dynamics calculations of 100 eV to 6 keV incident particles scattering from single crystal surfaces are performed using three particle interaction models. We find that for some incident conditions, a simultaneous interaction model is needed to produce accurate trajectory simulations. This extended model takes into account the simultaneous interactions among the primary particle and all the other atoms in the system but not the ones among the substrate atoms. A fair agreement between the calculated results of this extended interaction model and that of the full dynamics model is observed for nearly the entire energy regime studied. The range of primary energies where the binary collision model is adequate in describing forward scattering processes is discussed. 1. Introduction As one of the oldest tools for surface characterization, the interaction of energetic particles [l-19] with solids (molecular [l], ionic [3,6-151, and atomic [2,4,5] is widely used in a variety of applications. The nature of the interaction with solid surfaces can be roughly categorized according to the magnitude of the incident beam energy. At very low (- lo-100 mev) energy i.e. the particle-surface interaction potential is weak and the quantum effects are apparent [1,2]. These particles exhibit strong specular peaks in the angular scattering distribution and, in the case of light particles such as H, and He, diffraction is observed. In the high (100 keV-100 MeV) incident energy regime [3] where Rutherford scattering is the dominant mechanism, the surface is strongly corrugated. Information on the atomic composition and the depth profile of surfaces is derived from classical dynamics using the two-body interaction model. At incident energies intermediate between the two ex- tremes, the theoretical description of particle-surface interactions is more * Present address: Department of Chemistry, University of Hawaii, Honolulu, HI 96822, USA. ** Camille and Henry Dreyfus Teacher-Scholar. 0039-6028/ 88/ $03.50 0 Elsevier Science Publishers B.V. (North-Holland Physics Publishing Division)