arXiv subjects

Glen P. Kiely

Publications and source records attributed to Glen P. Kiely.

3 recordsLinked to original sources

arXiv2026

Validation of an Ab Initio-Informed Electronic Stopping Model for Large-Scale Atomistic Simulations

Accurately modeling nonadiabatic electronic energy dissipation in atomistic simulations of radiation damage remains a key challenge. Existing models often rely on arbitrary thresholds and neglect trajectory-dependent, band-structure, and nonlinear effects. A model developed by Tamm \textit{et al.} (\href{https://doi.org/10.1103/PhysRevLett.120.185501}{doi:10.1103/PhysRevLett.120.185501}) offers a nonempirical description of electronic dissipation for atomistic simulations, but has not been directly benchmarked in the electronic stopping regime. We present the first such benchmark via the comparison of atomistic simulations with experimental ion transmission experiments. The model accurately captures the magnitude and trajectory-dependence of the predicted energy losses. These results support the reliability of the model for predictive large-scale atomistic simulations of radiation cascades.

cond-mat.mtrl-sci↗

arXiv2025

Trajectory-Dependent Electronic Energy Losses in Ion Range Simulations

The energy losses of energetic ions in materials depend on both nuclear and electronic interactions. In channeling geometries, the stopping effect of these interactions can be highly reduced, resulting in deeper ion penetration. Comprehensive, trajectory-dependent models for ion-material interactions are therefore crucial for the accurate prediction of ion range profiles. We present the implementation of a recent electron density-dependent energy-loss model in the efficient molecular dynamics-based MDRANGE code. The model captures \textit{ab initio} electron dynamics using a parametrized ion energy loss function, based on calculations for explicit trajectories using real-time time-dependent density functional theory. We demonstrate the efficient simulation of trajectory-dependent ion range profiles with this comprehensive model for electronic energy losses. Our results indicate that accurate trajectory-dependent ion range profiles can be simulated using well-fitted parametrizations of this model. This method offers a unique tool for validation of the fitted energy-loss functions using energetic ion ranges, which can be measured experimentally but are beyond the capability of full MD simulations due to the computational expense.

cond-mat.mtrl-sci↗

arXiv2024

Electronic effects in radiation-induced collision cascades in nickel

The accurate treatment of electronic effects in multi-million atom simulations of radiation-induced collision cascades is crucial for reliable predictions of primary radiation damage. In this work, we explore the performance of a recently developed two-temperature molecular dynamics model implementing an electron density-dependent coupling of electronic and atomic subsystems for cascade simulations in nickel. We show that the parameter-free model realistically captures the instantaneous energy losses during all stages of the highly non-equilibrium cascade process. Simulations predict two distinct coupling regimes, corresponding to the rapid electronic stopping energy losses in the early stages of the cascade and to the electron-phonon coupling mechanism in the later stages, without the use of separate coupling terms. The intermediate stage of the cascade dynamics displays a complex energy transfer between the subsystems, which cannot be validated by comparison to either electronic stopping or electron-phonon coupling theories. We therefore compare the predicted atomic mixing, which is sensitive to the energy losses during the intermediate cascade stage, with experimental ion beam mixing measurements. We find good agreement with the experiments, validating the coupling model for the intermediate stage of cascades. Predictions of final defect numbers and cluster sizes are found in line with the predictions of conventional electronic stopping-based methods, while significantly reducing the theoretical uncertainty in the predictions of conventional models stemming from arbitrary choices of thresholds for different coupling terms. Our results represent a notable improvement in cascade damage predictions in nickel, providing validation of the electron density-dependent coupling model for radiation damage simulations in general.

cond-mat.mtrl-sci↗