Calculations of range parameters for heavy ions in carbon using ab initio potentials

Interatomic potentials for Kr–C, Xe–C and Au–C systems have been calculated with Hartree–Fock (HF) and density–functional theory (DFT) methods in order to clarify the origins of discrepancies between available experimental data and the values predicted by Ziegler, Biersack and Littmark (ZBL) theory for range parameters of heavy ions in light targets at energies of about 1–1000 keV. Relativistic effects were taken into account in the evaluations of the potentials. Range parameters have been obtained within the framework of the standard transport theory. Good agreement between the calculated projected ranges and the experimental data in the energy range of 10 to 1000 keV gives use in the range–projection equations the nuclear stopping powers, determined with first-principles potentials, and the velocity-proportional electronic stopping powers by Land and Brennan (LB). Considerable improvement has also been achieved in the description of the projected range straggling. It is concluded that correlations between the nuclear and electronic energy losses can be neglected in the studied energy range.