Compton spectroscopy to study electronic response of orthorhombic potassium niobate

We report Compton profile (CP) of KNbO3 by emoloying 100 mCi241 Am Compton spectrometer. Duly processed experimental CP is compared with theoretical profiles derived using different exchange and correlation functionals namely Perdew-Burke-Ernzerhof(PBE) and Perdew-Wang (PW) within the generalized gradient approximation (GGA) and local density approximation (LDA) with Lee-Yang-Parr (LYP) as facilitated in linear combination of atomic orbitals computations. It is observed that the CP derived using GGA-PW theory gives better agreement with the experimental profile than LDA-LYP and GGA-PBE approximations. We also present the density of states and energy bands which imply an indirect band gap (1.85 eV) of the compound. Further, it is observed that O-2p and Nb-4d electronic states mainly form the valence and conduction bands, respectively and are majorly responsible for the indirect band gap. Hybridization of O-2p and Nb-4d states is witnessed in the upper valence region.