The backscattering from and the implantation of 0.5–10‐keV hydrogen and helium in Au is investigated with the MARLOWE and TRIM computer codes. The following are found in this paper: (1) The results of the MARLOWE and the much faster TRIM codes are in satisfactory agreement. (2) The influence of potential parameters and energy loss models (LSS and Oen‐Robinson) is mainly on the heights and to less extent on the shapes of the energy distributions of backscattered particles. (3) The experimental data from the preceding paper favor the use of a potential for the calculation, which is weaker than the Molie`re potential. This can be simulated by using a screening length smaller than the Firsov value.