  Quaternary chalcogenide compositions have been broadly explored due to their
promising potential for various optoelectronic applications. The band
structure, density of states and optical properties of CuZn2InS4 and CuZn2GaS4
for kesterite and stannite structures were studied with full potential
augmented plane wave method (FP-LAPW) via Wien2k code. The total energy in
equilibrium was calculated for different possible crystal structures and their
phase stability, and transitions with p-d orbitals were analyzed. The
absorption coefficient, dielectric function, and refractive index of these
materials were also explored within a broad range of energy. We compared the
calculated band gap values with available experimental results.
