Bond softness sensitive bond-valence parameters for crystal structure plausibility tests

<jats:p>Based on a description of bond valence as a function of valence electron density, a systematic bond softness sensitive approach to determine bond-valence parameters and related quantities such as coordination numbers is elaborated and applied to determine bond-valence parameters for 706 cation–anion pairs. While the approach is closely related to the earlier<jats:italic>softBV</jats:italic>parameter set, the new<jats:italic>softNC1</jats:italic>parameters proposed in this work may be simpler to apply in plausibility checks of crystal structures, as they follow the first coordination shell convention. The performance of this<jats:italic>softNC1</jats:italic>bond-valence parameter set is compared with that of the previously derived<jats:italic>softBV</jats:italic>parameter set that also factors in contributions from higher coordination shells, and with a benchmarking parameter set that has been optimized following the conventional choice of a universal value of the bond-valence parameter<jats:italic>b</jats:italic>. The results show that a systematic adaptation of the bond-valence parameters to the bond softness leads to a significant improvement in the bond-valence parameters, particularly for bonds involving soft anions, and is safer than individual free refinements of both<jats:italic>R</jats:italic><jats:sub>0</jats:sub>and<jats:italic>b</jats:italic>from a limited number of reference cation environments.</jats:p>