Introduction . Density functional theory (DFT)1 , 2 , 3has enabled accurate, ab initio predictions of materials properties and explanations of a wide range of experimental data. Tens of thousands of DFT calculations are performed each year. The reliability of DFT predictions has led to materials-genome-type projects4 , 5 , 6 , 7, in which a large set of possible material compositions and structures are screened by DFT calculations in order to identify those with pro...