Ab initio calculations of the electron spectrum and density of states of TlFeS$_{2}$ and TlFeSe$_{2}$ crystals

The results of ab initio calculations of the electron spectrum of TlFeS$_{2}$ and TlFeSe$_{2}$ crystals in the antiferromagnetic phase are reported. Calculations are carried out in the context of the density functional theory. The origin of the bands of $s$, $p$, and $d$ electron states of Tl, Fe, S, and Se atoms is studied. It is established that, in the antiferromagnetic phase, the crystals possess semiconductor properties. The band gaps are found to be 0.05 and 0.34 eV for TlFeS$_{2}$ and TlFeSe$_{2}$ crystals, respectively.