Solid-state high-order harmonic generation in different bases: Convergence and physical validity of truncated representations
Phys. Rev. A 113, 063101 – Published 2 June, 2026
DOI: https://doi.org/10.1103/szp7-cml4
Abstract
In this work, we investigate the convergence and physical reliability of truncated-basis representations in solid-state high-order harmonic generation by comparing the stationary Bloch and accelerated Bloch bases. We show that the two representations exhibit intrinsic numerical inequivalence under strong-field driving, leading to distinct carrier dynamics and harmonic emission. Consistent with previous studies, the convergence behaviors of the two bases with respect to the number of retained bands differ qualitatively, with the accelerated Bloch basis achieving reliable spectral convergence using significantly fewer bands. By analyzing the deviation between truncated-band and full-band results, we show that the energetically remote bands affect the harmonic generation through two distinct mechanisms: the population leakage into other bands, which mainly leads to intensity renormalization, and the modifications of the interband polarization phase within the truncated subspace, which cause structural distortions of the spectrum. These multiband effects can be systematically incorporated into reduced two-band descriptions through a band-folding correction. Our results provide a physically transparent procedure for assessing truncated-basis convergence and offer practical guidance for efficient reduced-basis modeling of strong-field electron dynamics in crystalline solids.
