Assessment of hybrid density functional in revealing electronic response and half-metallic character of TM2O3 (TM = Ti, V and Cr) and their Compton spectroscopy

Compton profiles (CPs) of TM2O3 (TM = Ti, V and Cr) have been measured using 100 mCi Am-241 Compton spectrometer. The experimental momentum densities have been used to check the applicability of exchange-correlation energies using pure and hybrid density functional theory (DFT). Present ab-initio computations have been accomplished using the texture of Gaussian orbitals within linear combination of atomic orbitals (LCAO) scheme. Based on experimental and theoretical CPs, hybrid DFT schemes namely B3LYP and PBESOL0 have shown better performance than pure DFT (within local density and generalized gradient approximation), whereas the best agreement (through chi(2) fitting of goodness) is obtained for B3LYP prescriptions. Besides Compton spectroscopy, the spin-up (up arrow) energy bands and density of states (DOS) have confirmed the metallic nature of all three compounds, whereas the spin-down (down arrow) energy bands and DOS for Ti2O3 and V2O3 have shown a peculiar semiconducting behaviour leading to their very peculiar half-metallic character. Further, higher values of charge transfer from all the 3d transition elements to O atoms, as witnessed using Mulliken's population analysis, show a dominancy of ionic nature in these oxides. Equally normalized CPs of these oxides show that the 3d electrons in oxide environment are delocalized (in real space) in the ascending sequence Cr -> V -> Ti, which is in contrast to their elemental-free atom environment.

Automated summary

The Compton profiles (CPs) of TM2O3 (TM = Ti, V, and Cr) were measured using a Compton spectrometer. The experimental and theoretical results showed that the hybrid density functional theory (DFT) schemes B3LYP and PBESOL0 performed better in describing the properties of TM2O3 compounds compared to pure DFT. The spin energy bands and density of states (DOS) confirmed the metallic nature of all three compounds, while Ti2O3 and V2O3 showed peculiar semiconducting behavior and half-metallic character. The charge transfer analysis showed a dominance of ionic nature in these oxides. The normalized CPs indicated that the delocalization of 3d electrons in oxide environment followed the sequence Cr -> V -> Ti, contrasting their behavior in elemental-free atom environment.