Band structure and optical properties of some quasi-molecular AI3 (A=Sb, Bi, As)

We perform first principles density functional pseudopotential calculation for the description of band structure and optical responses a prototypical family of quasi-molecular layered solid of the type AI3 where Sb Bi and As. Our report on calculation of the anisotropic frequency-dependent optical properties and density of states of these compounds and find excellent agreement with the available experimental data. The optical properties show two main structures that can attributed to transitions between the np-orbitals of A+3 - cations and 5 s2 5 p5 orbitals of I I- -anions.