Theoretical and experimental study of the niobium dioxide electronic structure

The investigation of the niobium dioxide electron-energy structure is presented in the paper. The electronic structure computer modeling of the NbO2 with a rutile crystal structure has been performed using linearized augmented plane wave method. The energy band structure as well as total and partial densities of electronic states are calculated. Experimental studies of the NbO2 sample electronic structure were carried out using synchrotron and laboratory X-rays sources. The X-ray photoelectron spectrum of the valence band and subvalent states of NbO2 and the spectrum of the X-ray absorption near edge structure near K-edge of the oxygen atom in NbO2 have been recorded. The spectra of the X-ray absorption near edge structure of the oxygen and niobium atoms K-edges are modeled. The calculated spectra make it possible to reliably interpret the data from the synchrotron experiment. It is shown that for NbO2 the spectrum calculated for the ground energy state without using the supercell and core hole modeling method demonstrates high agreement with the experiment