For the comparison of the peak shape of cubic Yb 2 O 3 and the experimental result by Altman et al. , the spectrum with a smaller smearing width (0.2 eV) is shown as the orange dashed line in Fig. . The finer spectrum agrees with the experimental one with respect to the following two points: (i) Peak A comprises two split peaks and (ii) a small peak is present between peaks A and B. The small peaks at approximately 3-4 eV higher than peak B observed in our simulated spectrum were considered a single peak and assigned as the same bonding type as peak B in the experimental work. A small peak near the threshold energy in the measured spectrum is missed in our calculated one. This suggests that the peak originates from a factor ignored in our calculation framework, namely, the existence of unoccupied 4f orbitals in the Yb potential and Yb 2+ ions. Furthermore, the origin of the peak is the presence of unoccupied 4f orbitals near the conduction band minimum, which were not treated in the Yb potential as valence electrons in our calculation framework. This comparison using the small smearing width corroborates our calculation methodology.