these require the solution of the Schoedinger equation using the long-range Coulomb potential which is incompatible with the concept of a localized bond. History The bond valence method is a development of Pauling's rules. In 1930, Lawrence Bragg showed that Pauling's electrostatic valence rule could be represented by electrostatic lines of force emanating from cations in proportion to the cation charge and ending on anions. The lines of force are divided equally between the bonds to the corners of the coordination polyhedron. Starting with Pauling in 1947 a correlation between cation–anion bond length and bond strength was noted. It was shown later that if bond lengths were included in the calculation of bond strength, its accuracy was improved, and this revised method of calculation was termed the bond valence. These new insights were developed by later workers culminating in the set of rules termed the bond valence model. Actinide oxides It is possible by bond valence calculations to estimate how great a contribution a given oxygen atom is making to the assumed valence of uranium. Zachariasen lists the parameters to allow such calculations to be done for many of the actinides. Bond valence calculations use parameters which are estimated after examining a large number of crystal structures of uranium oxides (and related uranium compounds); note that the oxidation states which this method provides are only a guide which assists in the understanding of a crystal structure. For uranium binding to oxygen the constants R0 and B are tabulated in the table below. For each oxidation state use the parameters from the table shown below. Doing the calculations It is possible to do these simple calculations on paper or to use software. A program which does it can be obtained free of charge. In 2020 David Brown published a nearly comprehensive set of bond valence parameters on the IuCr web site. References Chemical bonding Coordination chemistry