ure 7 presents a side-by-side comparison of the HHG spectra computed with and without a cap. At both the HF and LRC-ωPBE levels of theory, the noise in the original spectrum (sans CAP) is greatly reduced and consequently distinct peaks emerge at odd harmonic orders, as anticipated. The two spectra (HF and LRC-ωPBE) computed with a CAP are compared side-by-side in Fig. . Up to the 20th harmonic, the TDHF and TDKS results match relatively well but the TDHF spectrum subsequently falls off much more rapidly between the 20th and 30th harmonics. Above the 30th harmonic, the LRC-ωPBE spectrum continues to exhibit markedly larger intensity. There are also some resurgent peaks (a.u.)