High-order harmonic generation in solid slabs beyond the single active electron

TL;DR

This paper uses time-dependent density functional theory to simulate high-harmonic generation in solid slabs, revealing multiple harmonic plateaus at low field strengths and analyzing their origins in band structure dynamics.

Contribution

It demonstrates the occurrence of high-order harmonics beyond single-electron models and explains the plateau cutoffs via band gap considerations.

Findings

Multiple harmonic plateaus observed at low intensities

Full spectra differ from individual Kohn-Sham orbitals

Freezing the Kohn-Sham potential is a good approximation

Abstract

High-harmonic generation by a laser-driven solid slab is simulated using time-dependent density functional theory. Multiple harmonic plateaus up to very high harmonic orders are observed already at surprisingly low field strengths. The full all-electron harmonic spectra are, in general, very different from those of any individual Kohn-Sham orbital. Freezing the Kohn-Sham potential instead is found to be a good approximation for the laser intensities and harmonic orders considered. The origins of the plateau cutoffs are explained in terms of band gaps that can be reached by Kohn-Sham electrons and holes moving through the band structure.