Electronic structure of nonstoichiometric compounds in the coherent potential approximation

We formulate and implement a method for electronic structure calculations based on the coherent potential approximation. This method provides an accurate description for nonstoichiometric compounds with the disordered location of vacancies. In the essence of its formulation, the method is similar to the implementation of the local electron density approximation in combination with the dynamical mean field theory (LDA+DMFT) and, hence, it can be easily incorporated in the latter approach. We study the evolution of the electronic structure of titanium dioxide TiO$_{2-\delta}$ (rutile) with the growth of nonstoichiometry in the oxygen sublattice. The results of the calculations are compared to the experimental data on the photoemission spectra.