Covalency, central field, significance

If we accept eq. (19) destroying the validity of / = 2 when 63 and 6s are different from zero, we may make the approximation that only the part of the orbital concentrated on the central ion makes a significant contribution to the interelectronic repulsion. Since the effect of the central-field covalency can be represented by... 

Gerloch and Woolley reformulated the AOM in a way that resolves some of the difficulties encountered with, for example, square planar CuCLi , but rejects parameter transferability. The LF parameters are determined from both optical and magnetic data, with SO coupling taken fully into account. The five-orbital model, which lies at the heart of LF theory is retained the d orbitals, it is argued, are not significantly involved in covalency and remain pure , albeit with expanded radial functions as a consequence of central-field covalence. 

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