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 241Am 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 χ2 fitting of goodness) is obtained for B3LYP prescriptions. Besides Compton spectroscopy, the spin-up (↑) energy bands and density of states (DOS) have confirmed the metallic nature of all three compounds, whereas the spin-down (↓) 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. [ABSTRACT FROM AUTHOR]