Electronic structure of the CuBS2 crystal

The band structure and spectra of the total and projected densities of states of a new crystal of the chalcopyrite family, namely, CuBS2, have been calculated in terms of the density functional theory. It has been found that the crystal is a pseudo-direct-band-gap semiconductor, and the best theoretical estimate of the optical band gap is 3.44 eV. The upper valence band of the CuBS2 crystal basically consists of the contributions from the p states of S atoms and the d states of Cu atoms. The crystal splitting is 0.2 eV. The bottom of the conduction band is basically formed by the sp states of boron and sulfur atoms with an admixture of the s states of copper atoms.