Computer simulation of the reflection of energetic ions from crystal surfaces at glancing incidence

A two-dimensional classical dynamics model for calculation of the reflection coefficient for scattering of keV beams at glancing incidence using potentials with cylindrical symmetry is presented. The target in the model consists of a single layer or two layers of atomic strings and reflects the (111) surface in the most open [1 (1) over bar 0], direction. The critical transverse energy of several primary ions for total reflection (100% reflection) from the surface is determined for Al, Ag, Au, Cu, Ni and Pt crystal (111) surfaces. The results are obtained using cylindrical potentials constructed from recently updated "individual" ion-surface interaction pair potential. We compare the results of the simulation with the 2-D row-model to experimental data for the energy losses. The model most suitable for describing these data is the Oen-Robinson empirical formula for the inelastic losses. Various expressions for the position-dependent friction force as a function of the local electron density are investigated. For the last simulation, the electron density is averaged over the atomic rows in a manner similar to the construction of cylindrical potentials according to Lindhard's theory. The simulations with the 2-D row-model are available as a compact computer code with good visualization. (C) 1999 Elsevier Science B.V, All rights reserved.