Which orbital interactions should be considered

At the beginning of Section 2.3 we stated some general requirements that should be met for orbital interactions to take place efficiently. We stated that orbital interactions are 

The energy separation AE in Fig. 2.13 is critical. If it is large, interaction between V y will be poor (the over- 

At the beginning of Section 1.13 we stated some general requirements that should be met for orbital interactions to take place efficiently. We stated that orbital interactions are allowed if the symmetries of the atomic orbitals are compatible with one another. In our approach to the bonding in a diatomic, we made the assumption that only the interactions between like atomic orbitals, e.g. 2 -2,  

need be considered. Such interactions are symmetry-allowed, and in addition, in a homonuclear diatomic the energies of like atomic orbitals on the two atoms are exactly matched. 

In a heteronuclear diatomic, we often encounter two atoms that have different basis sets of atomic orbitals, or have sets of similar atomic orbitals lying at different energies. For example, in CO, although both C and O possess valence 2s and 

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