Theoretical Calculation of ELNES Using First Principles Band Structure Methods

This paper reviews theoretical calculation of ELNES using first principles band structure methods. A core-hole is included in the calculation, and the matrix elements of the electric dipole transition between the ground state and the final state are computed. The satisfactory reproductions of the experimental spectra are commonly brought about by employing the sufficient large supercells. The orientation dependence of ELVES for wurtzite-A1N is discussed. The dependence was found to be much larger in K edges as compared to the L2.3 edge. The large projection dependence is predicted in O-K ELNES of SrTiO3. It was found that those spectral changes according to the position of the projection are caused by the unidirectional Ti-O-Ti bond in SrTiO3. Theoretical calculation of the low loss spectrum from SrTiO3 is also discussed.