Resonant inelastic X-ray scattering (RIXS) is a powerful technique for studying elementary excitations due to its element and orbital specificity, as well as its access to a wide range of energies and momenta. The theoretical description of the RIXS double differential cross-section is typically carried out using all-electron calculations. Here, we present a study of shallow-core excitations at the L-edges of aluminum in α-Al2O3 using a pseudopotential plane-wave framework. Since strong excitonic effects have been observed in the optical [1] and core [2] absorption spectra of alumina, we perform the calculations using the Bethe-Salpeter equation (BSE), which is the state-of-the-art technique for describing electron-hole interactions. 

In our work, we address the question of the validity of the pseudopotential approximation for RIXS spectra of shallow-core edges. We investigate the limits of the pseudization of the wave functions in many-body BSE calculations and the advantages of treating all the valence and shallow-core electrons on the same footing.

 

 

[1] Marinopoulos et.al, Phys. Rev. B 83 (2011) 195129
[2] Mogi et.al, Materials Transactions, 45 (2004) 2031-2034