Nondegenerate interaction

When e° e° without loss of generality e° may be assumed to be lower in energy than e°, that is, e° — e° 0. Rearrangement of equation 2.6 leads to 

Approximate expressions for ei and e2 are found as foiiows. First D can be expanded as 

The orbital energies are shown pictorially in 2.6. As a result of the interaction, the lower level e° is depressed in energy, and the higher level e° is raised in energy. 

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FIGURE 2.2.. Molecular orbital diagram showing delails of the nondegenerate interaction between two atomici orbitals, xi X2-... 

The weight of is reduced from one by every nondegenerate interaction i// makes with various orbitals i//y. In most cases of our qualitative application of perturbation theory, it is sufficient to remember that the weight of the leading term... 

This describes a nondegenerate interaction between the levels sing the... 

It is of interest to compare the nature of the HOMOs in 10-electron systems Nj and CO. The HOMO 2o of N3 shown in Figure is stabilized by d eneiate orbital interaction but destabilized via nondegenerate interaction (see 6.4). If the non-degenerate contribution is larger than the degenerate one then this orbital too can... 

Finally, we briefly comment on those cases in which neither the degenerate nor the nondegenerate perturbation treatment is quite satisfectory [5]. To simplify our discussion, let us consider only the lower lying orbital and its ener gy e, that result from two interacting orbitals and For a nondegenerate interaction with... 

Nondegenerate interactions for H4 using the results from Figure 5.8. 

This describes a nondegenerate interaction between the ieveis ots and ot s. Using the ideas of Section 3.2, the energies of the two bands become... 

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