Bond-length distributions in ionically bonded materials with decomposition by coordination environment.

The distributions are analysed of the bond lengths between cations and anions in nitrides, oxides and fluorides for which structural data are available in the Crystallography Open Database (https://www.crystallography.net/cod/). The distributions are decomposed according to analysis of the coordination environments of the cations, which are offered in the tool [Waroquiers, George, Horton, Schenk, Persson, Rignanese, Gonze & Hautier (2020). B, 683-695]. The distributions show how well the concept of ionic radius works. Chemical trends can be observed from the obtained distributions. For example, the bond-length distribution for Sc-O is similar to that for Zr-O. The distributions for Mo-O and V-O show noteworthy similarity. Resources for reproducing all of the results are available at https://github.com/tkotani/CEBond, with additional results for nitrides and fluorides.