Guidelines for robust and reproducible point defect simulations in crystals

Many physical properties of functional materials are governed by their impurities rather than their bulk characteristics. Defects in crystals can activate electronic and ionic conductivity, create active centres for catalysis, or store information through localised spin configurations. Accurate modelling of defect behaviour is therefore essential for predicting material performance and optimising functionality across a vast application space. However, defect simulations are sensitive to choices made during setup, execution, and analysis. In this perspective, we highlight best practices for calculating and reporting defect properties through computational methods, with a focus on the widely-adopted supercell approach. Key considerations include accurate representation of the structural and electronic properties of the host material, appropriately choice of charge states, sufficient optimisation of defect geometries, and reproducibly calculating defect formation energies. Adhering to these practices will facilitate robust comparisons between studies and improve the integration of computational predictions with experimental results. We emphasise the importance of reporting computational parameters and correction schemes. Ultimately, an open approach to defect simulations will strengthen the impact of computational studies and accelerate materials engineering.