Incorporating non-adiabatic effects in embedded atom potentials for radiation damage cascade simulations

Area of Science:

• Materials Science
• Computational Physics
• Nuclear Engineering

Background:

• Radiation damage cascades involve ions and electrons reaching high, non-equilibrium temperatures.
• Accurate molecular dynamics (MD) simulations need to model non-adiabatic energy exchange between electrons and ions.

Purpose of the Study:

• To develop a consistent model for electronic stopping, temperature rise, and thermal conduction in MD simulations.
• To present a scheme for correcting empirical potentials to include non-adiabatic effects.
• To parameterize these corrections for bcc transition metals.

Main Methods:

• Developed a correction scheme for embedded atom potentials based on the second-moment approximation.
• Parameterized the corrections for bcc transition metals above the Debye temperature.
• Utilized two-temperature MD simulations to assess the impact of electronic thermal conductivity.

Main Results:

• The proposed scheme corrects empirical potentials for non-adiabatic ion-electron energy exchange.
• Electronic thermal conductivity significantly impacts heat exchange between ions and electrons during cascade evolution.
• Corrections are applicable to various empirical potentials, including Finnis-Sinclair and Derlet-Nguyen-Manh-Dudarev models.

Conclusions:

• Accurate modeling of radiation damage cascades necessitates incorporating non-adiabatic electron-ion energy transfer.
• The presented correction scheme enhances the fidelity of MD simulations for materials under irradiation.
• Computing electronic thermal conductivity is crucial for understanding heat dissipation in displacement spikes.