On the yet not fully elucidated ground states physical properties of the ternary chalcogenides AGAS, (A = K, Rb, Cs)

Abstract

We present here the results of a first principle principle study on the structural, electronie and optical properties of AGAS: (A-K, Rb, Cs) compounds using the plane wave pseudo- potential method. The exchange correlation potential was treated within the generalized gradient approximation (GGA) as implemented in the CASTEP code and expressed by the PBE functional. The equilibrium lattice parameters are in good agreement with the available experimental results. The calculated band structure show that the studied compounds are direct moderate gap semiconductors. A set of frequency dependent optical parameters were calculated including the complex dielectric function, the reflective index and the absorption coefficient. The obtained results show that the herein considered compounds are active in the UV region.