Many-body embedded-atom potential for describing the energy and angular distributions of Rh atoms desorbed from ion-bombarded Rh{111}

In this paper, we show that many-body interactions are important for describing the energy- and angle-resolved distributions of neutral Rh atoms ejected from keV-ion-bombarded Rh{111}. We compare separate classical-dynamics simulations of the sputtering process assuming either a many-body potential or a pairwise additive potential. The many-body potential is constructed using the embedded-atom method to describe equilibrium properties of the crystal, parameters from the Molière potential to describe close encounters between energized atoms, and parameters from a Rh2 potential to aid the description of the desorption event. The most dramatic difference between the many-body potential and the pair potential is in the predicted kinetic energy distributions. The pair-potential kinetic energy distribution peaks at 2 eV, whereas the many-body potential predicts a broader peak at 4 eV, giving much better agreement with experiment. This difference between the model potentials is due to the predicted nature of the attractive interaction in the surface region through which all ejecting particles pass. Variations of the many-body-potential parameters are examined in order to ascertain their effect on the predicted energy and angular distributions. A specific set of parameters has been found which leads to excellent agreement with recent experimental trajectory measurements of desorbed Rh atoms.