Radiation damage induced by high-energy neutron irradiation in nuclear reactor environments is the primary cause of macroscopic property degradation in nuclear materials. Although molecular dynamics (MD) simulations have been extensively applied to probe the atomic-scale evolution of radiation damage, the predictive accuracy of such simulations is strongly dependent on the interatomic potentials adopted. In this study, MD simulations were performed to systematically investigate the distinct effects of the short- and long-range components of interatomic potentials on primary knock-on atom (PKA)-induced cascade evolution in body-centered cubic tungsten (W).
Two well-validated many-body potentials for W, namely the Finnis-Sinclair-type potential developed by Ackland and Thetford (AT potential) and the EAM-type potential proposed by Mason et al. (MN potential), were employed for the simulations. To examine the influence of short-range interactions, six hybrid potentials were constructed by combining the two base potentials with three screened Coulomb potentials (Ziegler-Biersack-Littmark, Molière, and Kr-C). Additionally, a switching function was adopted to modify the long-range region of the MN potential to evaluate the influence of long-range interactions. Simulations were performed at three PKA energies (20, 50, and 80 keV), with 30 independent calculations conducted for each condition to ensure the statistical reliability of the results.
The simulation results reveal that the short-range repulsion of interatomic potentials dominates the energy transfer efficiency and spatial distribution of collision cascades. A stiffer short-range potential constrains the penetration of high-energy PKAs, inhibits subcascade formation, and produces dense thermal spikes. Such behaviors increase the defect yield at the thermal spike phase, enhance defect recombination efficiency, and promote the formation of large-sized defect clusters and dislocation loops. Conversely, modifying the long-range potential region primarily alters the equilibrium thermodynamic properties of W, including its melting point, as well as the formation and binding energies of vacancies and self-interstitial atoms. While the long-range potential component exerts a negligible influence on the total number of cascade-induced defects, it substantially affects subcascade splitting, the clustering of surviving defects, and the number and total length of dislocation loops.
This study clarifies the respective roles of short- and long-range potential components in cascade damage, serving as a valuable reference for the selection and optimization of interatomic potentials in MD simulations of radiation damage in W.