First principles calculations of structural, electronic, optical and thermodynamic properties of PbS, SrS and their ternary alloys Pb1−xSrxS

► Determination of ground properties such as lattice parameter and bulk modulus. ► Investigation of band-gap energy and its variation versus composition, and determination of gap bowing which is related to the disorder in the alloys. ► Transition of the gap from direct to indirect. ► Determination of the optical properties such as the optical transitions. ► Thermodynamic stability of the alloys.