On the Absorption Spectra of Complex Ions, III The Calculation of the Crystalline Field Strength

A molecular calculation of the crystalline field parameter D q in chrome alum has been carried out on the basis of the generalized crystalline field model suggested in the previous papers I and II (Journ. Phys. Soc. Japan. 9 (1954) 753, 766). The deformation of the electron cloud of Cr 3+ is taken into consideration by making the 3d orbital of Cr 3+ orthogonal to ligand orbitals. The result shows that Kleiner's value of D q with a wrong sign is corrected. This improvement is due to the large resonance energy between the 3d orbitals of the central ion and the ligand orbitals, which appears only in the molecular treatment. However, the model Cr 3+ –6H 2 O cannot explain the observed change in the values of the spin orbit coupling constant λ and the B -value. A possible way to get over this difficulty is considered.