Understanding and rationalizing the structure of ionic solids by computational application of Beck's extended coordination number rule

Crystal chemical rules are widely applied to understand and rationalize inorganic crystal structures. Examples of such include Pauling rules and Beck's extended coordination number rule. For the latter no large-scale benchmark has been performed yet. A rigorous analysis of the validity of the extended coordination number rule was performed on a dataset consisting of 1044 ternary fluorides. 59.9% of the examined crystal structures agree with Beck's rule. An additional 22.3% of structures the deviations can be explained by a more or equally homogenous distribution of charges, thus yielding a total rationalization power of 82.2%. The structural complexity of the crystal structures was identified as a main reason for disagreement with Beck's rule.