https://www.selleckchem.com/products/en460.html Inverse Kohn-Sham (iKS) methods are needed to fully understand the one-to-one mapping between densities and potentials on which density functional theory is based. They can contribute to the construction of empirical exchange-correlation functionals and to the development of techniques for density-based embedding. Unlike the forward Kohn-Sham problems, numerical iKS problems are ill-posed and can be unstable. We discuss some of the fundamental and practical difficulties of iKS problems with constrained-optimization methods on finite basis sets. Various factors that affect the performance are systematically compared and discussed, both analytically and numerically, with a focus on two of the most practical methods the Wu-Yang method (WY) and the partial differential equation constrained optimization (PDE-CO). Our analysis of the WY and PDE-CO highlights the limitation of finite basis sets. We introduce new ideas to make iKS problems more tractable, provide an overall strategy for performing numerical density-to-potential inversions, and discuss challenges and future directions.Chalcogenide perovskites have emerged as lead-free, stable photovoltaic materials, having promising optoelectronic properties. However, a detailed theoretical study on excitonic properties is rather demanding task due to the huge computational cost and, therefore, is hitherto unknown. Here, we report the excitonic properties of chalcogenide perovskites AZrS3 (A = Ca, Sr, Ba) using state-of-the-art hybrid density functional theory and many-body perturbation theory (within the framework of GW and BSE). We find the exciton binding energy (EB) is larger than that of conventional halide perovskites. We also observe, by computing the electron-phonon coupling parameters, a more stable charge-separated polaronic state as compared to that of the bound exciton. The ionic contribution to dielectric screening is found to be negligible in this class of materia