Fission energy deposition in UO₂ through multi-scale/physics hierarchy modeling: From the first-principles and SRIM to molecular dynamics

As an alternative approach which takes advantages from previous two approaches, interactions of PKA with both excited electrons and surrounding atoms are described using multi-physics/multi-scale approaches. In quantum-mechanical approach using the first principle calculation, e-p coupling in UO₂ is described and related e-p coupling constants are calculated. From the calculated e-p coupling parameters, multiple heat deposition process including both electronic and lattice effects are simulated using classical molecular dynamics by two temperature model-MD (TTM-MD) frameworks. We have investigated the radiation damage effect on material using multi-scale/physics hierarchy. First, electron-phonon coupling parameters for heat diffusion equation between electron-phonon system is evaluated. Second, electronic stopping power is parameterized by SRIM calculation. From parameters from both approaches, TTM-MD framework has been simulated for accurate investigation of radiation effect on materials. Afterward, we have a plan to make the system size enlarged to describe high stopping range regime and have a comparison with track radius data created by irradiation experiment in same condition with our simulation.