On the Study of Racah Parameter B for Nickel (II) and Cobalt (II) Compounds
Keywords:Racah parameter, Metallic composites, Electronic transition.
The ligand field strength (Dq) and interelectronic repulsion (B) have been calculated for nickel (II) and cobalt (II) compounds by Underhill and Billing  based on v2 and v3 values. They solved the quadratic equation 340(Dq2-18(v2+v3) Dq+ v2 v3=0 in Dq for octahedral. Then, the B value was determined using the equation v2+ v3−30Dq−15B=0. But, the first equation has real and imaginary solutions and it’s difficult to determine the imaginary one. In addition, in many cases there is no solution of this equation as well as in the case of CoO (d7 oct.). For octahedral, the above two equations can be considered as a system of two equations with two unknowns which can be solved if we have v2 and v3 values and vice versa. Similarly, for tetrahedral, the former two equations also can be solved for Dq and B. Using Newton–Raphson iterations, Dq and B values are exactly determined for octahedral and tetrahedral systems. The obtained values of Dq and B were compared with those previously reported.
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