Orbital-Free Density-Functional Theory Simulations of Displacement Cascade in Aluminum

TL;DR

This paper uses orbital-free density-functional theory to simulate displacement cascades in aluminum, highlighting electronic effects like charge bridges and damping that influence damage evolution.

Contribution

It introduces OF DFT molecular dynamics for simulating displacement cascades, revealing electronic effects on damage processes not captured by classical MD.

Findings

OF DFT shows lower displacement spike peaks than classical MD.

Electronic damping shortens the duration of displacement spikes.

Charge density profiles reveal vacancy and interstitial clusters.

Abstract

Here, we report orbital-free density-functional theory (OF DFT) molecular dynamics simulations of the displacement cascade in aluminum. The electronic effect is our main concern. The displacement threshold energies are calculated using OF DFT and classical molecular dynamics (MD) and the comparison reveals the role of charge bridge. Compared to MD simulation, the displacement spike from OF DFT has a lower peak and shorter duration time, which is attributed to the effect of electronic damping. The charge density profiles clearly display the existence of depleted zones, vacancy and interstitial clusters. And it is found that the energy exchanges between ions and electrons are mainly contributed by the kinetic energies.