Band\nGaps of Hybrid Metal Halide Perovskites: Efficient\nEstimation

The employment of\nthe parameter-free Armiento–Kümmel\ngeneralized gradient approximation (AK13-GGA) exchange functional\nwas examined as a means of the band gap prediction for hybrid metal\nhalide perovskites (HaPs) or systems with strong spin–orbit\ncoupling in the full-relativistic density-functional theory (DFT)\ncalculations. A combination of AK13 with the nonseparable gradient\napproximation Minnesota correlation functional (GAM) was established\nas an approach allowing for the efficient band gap estimation with\naccuracy similar to the GW approximation method but at the computational\ncosts of conventional DFT. This was further supported by results of\nthe AK13/GAM calculations performed for various HaPs. The described\napproach creates an opportunity for the effective assessment of the\nelectronic structure of large, complex, doped, or defective HaPs and\nmodeling of advanced materials.