Comparison of repulsive interatomic potentials calculated with an all-electron DFT approach with experimental data

The interatomic potential determines the nuclear stopping power in materials. Most ion irradiation simulation models are based on the universal Ziegler-Biersack-Littmark (ZBL) potential (Ziegler et al., 1983), which, however, is an average and hence may not describe the stopping of all ion-material combinations well. Here we consider pair-specific interatomic potentials determined experimentally and by density-functional theory simulations with DMol approach (DMol software, 1997) to choose basic wave functions. The interatomic potentials calculated using the DMol approach demonstrate an unexpectedly good agreement with experimental data. Differences are mainly observed for heavy atom systems, which suggests they can be improved by extending a basis set and more accurately considering the relativistic effects. Experimental data prove that the approach of determining interatomic potentials from quasielastic scattering can be successfully used for modeling collision cascades in ion-solids collisions. The data obtained clearly indicate that the use of any universal potential is limited to internuclear distances R < 7 af (af is the Firsov length).