Study on electron momentum density of zinc and cadmium molybdates: First principles calculations and Compton spectroscopy

Abstract

We report first-ever Compton profiles of ZnMoO4 and CdMoO4 measured using photons of 661.65 keV emitted by 20 Ci 137Cs γ-ray source. To interpret the experimental momentum densities, we have also computed the electronic properties which include band structure, density of states (DOS), electron momentum density, Mulliken's population (MP), and anisotropy in Compton profiles using linear combination of atomic orbitals (LCAO) scheme with density functional theory. In addition, more accurate energy bands and DOS have been computed using full-potential linearized augmented plane wave method with modified Becke–Johnson potential (FP-LAPW-mBJ). The band gap values of ZnMoO4 and CdMoO4 calculated using FP-LAPW-mBJ approximation were found to be close to available experimental data. It is seen that momentum densities computed using LCAO scheme with PBEsol approximation gives a better agreement with the present measurements than other DFT approximations considered in the present work. On the basis of equal-valence-electron-density profiles, it is seen that ZnMoO4 has more covalent nature than CdMoO4 which is in tune with the present integrated DOS and Mulliken's population data.