Compton spectroscopy measurement of Eu₂O₃ and applicability of first and second order GGA in deducing electron momentum densities

First and second order generalized gradient approximations (GGA and SOGGA) within density functional theory (DFT) have been employed to compute the Mulliken populations (MP), energy bands, density of states (DOS) and Compton profiles (CPs) for heavy rare earth oxide namely Eu₂O₃. The DFT computations have been performed within linear combination of atomic orbitals (LCAO) method. Both the LCAO-GGA and -SOGGA based CPs have been compared with the present experimental CP measured using 20 Ci ¹³⁷Cs Compton spectrometer. It is found that both the computed CPs reconcile with the experimental Compton line shapes within the experimental errors. Present comparison shows equal role of exchange and correlation potentials of GGA and SOGGA in predicting the electronic structures of the studied oxide. The energy bands and DOS showed a metallic nature of the compound, while the large value of MP predicts the ionic character. Also, the anisotropies in CPs (J110-J100, J110-J100 and J111-J110) from GGA and SOGGA are found to be identical which strongly support the present conclusions. (author)