A software program, SPuDS (Structure Prediction Diagnostic Software) was developed to predict the crystal structures of perovskites, including those distorted by tilting of symmetric and Jahn-Teller distorted octahedra. Only the composition and oxidation states of the ions are required as user inputs. Rigid octahedra were maintained in electronically symmetric octahedra, while distortions of the octahedral bond lengths were utilized in Jahn-Teller distorted compositions. SPuDS calculates the optimal structure in Glazer tilt systems most often observed experimentally and for tilt systems with interesting multiple A-cation environments. Structure optimization occurs by distorting the structure to minimize the global instability index. Location of the A-site cation is chosen so as to maximize the symmetry of its coordination environment.
SPuDS has been employed in a number of useful applications, including the use of predicted structural information to estimate physical properties of both hypothetical compositions and those materials for which accurate structural data is not available, as a guide for exploratory synthetic efforts, as a starting model for Rietveld refinements in the course of structurally characterizing new materials, and for extracting the effects of octahedral tilting distortions from other structural distortion mechanisms. Structural predictions were made for a variety of compositions with a single and multiple octahedral cations and compared with a number of previously determined structures to illustrate the accuracy of this approach.