Time-Dependent Density-Functional Theory of Strong-Field Ionization of Atoms under Soft X-Rays

TL;DR

This paper demonstrates that time-dependent density functional theory (TDDFT) accurately models strong-field ionization of atoms under soft X-ray radiation, highlighting the importance of long-range interactions in the exchange-correlation potential.

Contribution

The study shows that TDDFT effectively describes ionization yields in soft X-ray regimes and evaluates the impact of different adiabatic density functionals on accuracy.

Findings

TDDFT matches experimental ionization yields for Ne and Ar.

Long-range exchange-correlation functionals are essential for accuracy.

TDDFT can distinguish contributions from individual ionization channels.

Abstract

We demonstrate the capabilities of time-dependent density functional theory (TDDFT) for strong-field, short wavelength (soft X-ray) physics, as compared to a formalism based on rate equations. We find that TDDFT provides a very good description of the total and individual ionization yields for Ne and Ar atoms exposed to strong laser pulses. We assess the reliability of different adiabatic density functionals and conclude that an accurate description of long-range interactions by the exchange and correlation potential is crucial for obtaining the correct ionization yield over a wide range of intensities ($10^{13}$ -- $5 \times 10^{15}$ W/cm$^2$). Our TDDFT calculations disentangle the contribution from each ionization channel based on the Kohn-Sham wavefunctions.