The accurate description of the O 1$s$ excitation in BaTiO${}_3$ has been elusive so far. In this Rapid Communication, the electronic structure and the high-resolution electron energy-loss near-edge structures of the O $K$ edge in tetragonal BaTiO${}_3$ are investigated using first-principles calculations. The results demonstrate a clear correlation between the broadening of the lower energy fine structure and the anisotropic effects induced by the core-hole potential, which are directly related to the structural distortion occurring in tetragonal BaTiO${}_3$. Moreover, we show that a significant improvement of the description of higher-lying structures can be obtained when correcting the energy position of the Ba 4$f$ states. This demonstrates that the O 1$s$ spectrum can be a very effective probe of the distortion and changes in the local electronic structure, and be used as a sensitive tool for studying new materials and ferroelectric transitions.

• Received 2 August 2013

DOI:https://doi.org/10.1103/PhysRevB.88.201107