Ab initio study of optical and bulk properties of cesium lead halide perovskite solid solutions

The first principles calculations of band gaps and bulk moduli of cesium lead halide perovskite solid solutions, $CsPb(I_{1-x}C{l}_x{)}_3$ and $CsPb(I_{1-x}B{r}_x{)}_3$, are performed at the level of general gradient approximation of the density functional theory. We use supercell approach for computational modeling of disordered systems, which gives a description of the properties of the structure basing on the average over a set of multiple onfigurations, namely distributions of different species over a given set of atomic positions. The calculations were performed with the CRYSTAL14 program package. The dependence of the band gap and bulk modulus on the content $x$ are investigated over the whole range $0\le x\le 1$.