The oxygen 1s x-ray-absorption spectra of ${\mathrm{SrTiO}}_3$ and ${\mathrm{TiO}}_2$, in both the rutile and anatase crystal structure, are analyzed using the oxygen p-projected density of states of ground-state band-structure calculations. Good agreement is found and it is concluded that multielectron effects, transition matrix elements, and the core-hole potential present only small, largely undetectable, influences on the spectral shape. From the site- and symmetry-projected density of states the rutile peaks could be assigned to the 3d band (4–8 eV), antibonding oxygen 2p states (10–18 eV), and the titanium 4sp band (20–25 eV). For anatase the titanium 4sp band is shifted to lower energy by about 5 eV, which can be related to the lower density of anatase. From differences in the crystal structure it is argued that the core-hole potential is considerably more effective in perovskite ${\mathrm{SrTiO}}_3$ than in both ${\mathrm{TiO}}_2$ crystal structures. This is in accordance with the experimental findings.

• Received 25 January 1993

DOI:https://doi.org/10.1103/PhysRevB.48.2074