Interelectron repulsion energy

We note that three spin-allowed electronic transitions should be observed in the d-d spectrum in each case. We have, thus, arrived at the same point established in Section 3.5. This time, however, we have used the so-called weak-field approach. Recall that the adjectives strong-field and weak-field refer to the magnitude of the crystal-field effect compared with the interelectron repulsion energies represented by the Coulomb term in the crystal-field Hamiltonian,... 

To obtain an accurate assessment of the interelectronic repulsion energy of the H2 molecule it is essential to carry out calculations in which the hydrogen nuclei are a constant distance apart. The following calculations are for an internuclear distance of 74 pm for both molecules, which is the equilibrium internuclear distance in the dihydrogen molecule. 

Table I Interelectronic repulsion energy in the frozen orbital approximation (C) and in the SCF approximation (C )(l).

In identifying the ground state for octahedral d, we are again faced with a conflict between considerations of orbital energy and of interelectron repulsion energy. The latter is... 

FIGURE 10-7 Enthalpies of Hydration of Transition Metal Ions. The lower curves show experimental values the upper curves result when contributions from spin-orbit splitting, a relaxation effect from contraction of the metal-ligand distance, and interelectronic repulsion energy are subtracted, (a) 2+ ions, (b) 3-b ions. (Reproduced with permission from D. A. Johnson and P. G. Nelson, Inorg. Chem., 1995, 34, 5666 data) and D. A. Johnson and P. G. Nelson, Inorg. Chem., 1999, 4949 data). 1995, 1999, American Chemical Society.)... 

A great deal of understanding about interelectronic repulsion energies is gained if one uses an approach explicitly showing the dependence of orbital energies with occupation numbers. This is the approach considered by the SCF—and related methods 51-54) and to these developments we turn now our attention. 

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