The Limited Predictive Power of the Pauling Rules

The Pauling rules have been used for decades to rationalise the crystal structures of ionic compounds. Despite their importance, there has been so far no statistical assessment of the performances of these five empirical rules. Here, we test rigorously and automatically all five Pauling rules for a large data set of around 5000 known oxides. We discuss each Pauling rule separately stressing their limits and range of application in terms of chemistries and structures. We conclude that only 13% of the oxides simultaneously satisfy the last four rules, indicating their much lower predictive power than expected.