Electronic energy loss assessment in theoretical modeling of primary radiation damage in tungsten

Reliable electronic energy loss needs to be accounted for to accurately estimate primary radiation damage of materials in theory. By introducing four types of electronic stopping cross-sections (Se) into the Monte Carlo (MC) code (IM3D) of collision cascade, and using an object kinetic MC model of short-term defect evolution, we studied the complete process of production and annealing of primary defects in tungsten (W) under high-energy (∼ MeV) self-ion and low-energy (∼ keV - hundreds keV) neutron-primary knock-on atom (PKA) irradiation. Different Se and their effects were evaluated to accurately estimate primary radiation damage. The difference in electronic energy loss changes the fraction of damage energy, affecting the number of primary defects and their spatial/size distributions. This effect is even pronounced with increasing initial energy, with deviations up to 40% and 60% for damage range and defect number, respectively. The simulation results with Se calculated by time-dependent density functional theory (TDDFT) are quantitatively consistent with experimental damage peaks in self-ion irradiated W and molecular dynamics simulated number of survival defects in neutron-PKA irradiated W. Thus, we recommend using Se calculated by TDDFT to estimate primary radiation damage in W with relative accuracy. It helps understand primary damage behaviors, further accurately simulate long-term defect evolution and predict properties of materials under irradiation.