Electronic structure of CuCl1-xBrx solid solutions: first-principles calculations in the meta-GGA approximation

The electronic structure of CuCl and CuBr compounds and their solid solutions CuCl1–xBrx (x = 0.25, 0.50, 0.75) has been calculated in the framework of the density functional theory. The calculations have been performed in the basis of pseudoatomic orbitals using the simple local approximation (LDA) and the new meta-GGA exchange potential TB09, which, to a large extent, compensates the LDA error in the description of the position of conduction bands in semiconductors. A comparative analysis of the main characteristics of the electronic structure of binary compounds and their solutions has been carried out. It has been found that the composition dependence of the band gap Eg(x) has a small downward bowing with the coefficient b ~ 0.09 eV