Mean bond-length variation in crystal structures: a bond-valence approach

The deficiencies present in the bond-valence theory in explaining mean bond-length variations observed in crystal structures can be overcome by taking into account the contribution of bond topology and bond strain to a constant bond-length value.

Bond valence at mixed occupancy sites. I. Regular polyhedra

Bond valence sum at mixed occupancy sites show the occurrence of systematic errors leading to apparent violations of the Valence Sum Rule as well as to erroneous bond strain values indicating underbonding or overbonding that actually does not exist.