Figure : Comparison of the scaled and unscaled harmonic IR spectrum of pyrene at the r 2 SCAN-3c level of theory with the experimental data from NIST Chemistry WebBook. The top theoretical trace shows a spectrum with the harmonic fundamentals, overtones, and combination bands, while the lower trace shows the harmonic spectrum with fundamental transitions only. ), for which the fingerprint region helium-tagging action spectrum was available. Here (Figure ), we observe the same trend as in the previous examples (Figures and): the s rel -scaled spectrum shows a good agreement with peak positions, whether the s abs -scaled spectrum overestimates the peak positions.