Time-dependent density functional theory of high-intensity, short-pulse laser irradiation on insulators

TL;DR

This paper uses time-dependent density functional theory to model energy deposition in insulators under high-intensity, short laser pulses, predicting damage thresholds and ablation depths with good accuracy.

Contribution

It introduces a multiscale real-time DFT approach with a meta-GGA potential to accurately simulate laser-induced damage in insulators.

Findings

Energy deposition correlates with laser fluence.

Ablation depth matches experimental data.

Damage threshold aligns with melting energy.

Abstract

We calculate the energy deposition by very short laser pulses in SiO_2 (alpha-quartz) with a view to establishing systematics for predicting damage and nanoparticle production. The theoretical framework is time-dependent density functional theory, implemented by the real-time method in a multiscale representation. For the most realistic simulations we employ a meta-GGA Kohn-Sham potential similar to that of Becke and Johnson. We find that the deposited energy in the medium can be accurately modeled as a function of the local electromagnetic pulse fluence. The energy-deposition function can in turn be quite well fitted to the strong-field Keldysh formula for a range of intensities from below the melting threshold to well beyond the ablation threshold. We find reasonable agreement between the damage threshold and the energy required to melt the substrate. The ablation threshold estimated by the energy to convert the substrate to an atomic fluid is higher than the measurement, indicating significance of nonthermal nature of the process. A fair agreement is found for the depth of the ablation.