Band structure and optical functions of ternary chain TlInSe2 Original Research Article

The band structure of ternary chain TlInSe2 is calculated by a pseudo-potential method with allowance for non-locality of ionic pseudo-potentials. In the obtained band structure the symmetry and forbidden character of the direct transitions at band gap are ascertained to be the same as reported earlier from the results of the empirical pseudo-potential calculations. The imaginary part of the components parallel and perpendicular to the c-axis of the dielectric function tensor of TlInSe2 is calculated at photon energies up to 10 eV. The real part of these components is obtained by extrapolation of the imaginary part to higher energies and subsequent Kramers–Kronig transformation. The obtained dielectric function is compared with the one obtained ellipsometrically in the range 0.85–6.5 eV. The results of comparison are rather favorable.