Theoretical Calculation of Ground term for the Cr Atom
As we pointed out earlier there are some discrepancies from the expected filling of the Madelung prediction for half-filled and full filled d and f shells. Here we mainly concentrate on the Cr atom where the expected filling is 4s23d4 but the true occupation is 4s13d5. Here we mainly tried to find out the energy differences of these two different configurations by self consistently. It is obvious that the term symbol for 4s23d4 and 4s13d5 would be 5D and 7S respectively.
Many authors have calculated the Hartree-Fock energy of these two different configuration in order to work out the deviation from the Madelung rule. Hartree-Fock is the usual method for exploiting the exceptions of the Madelung rule. Apart from the literature, we have used the Gaussian Software to compute the total energies of the electronic configurations of the Cr atom. In table 1 we have compared those works in the literature with our results.