Some Simple Formulas for Elementary Interactions

In qualitative VB theory, it is customary to take the average value of the orbital energies as the origin for various quantities. With this convention, and using some simple algebra, the monoelectronic Hamiltonian between two orbitals becomes Pab, the familiar reduced resonance integral  

It is important to note that these p integrals, used in the VB framework are the same as those used in simple MO models such as extended Hiickel theory. 

Based on the new energy scale, the sum of orbital energies is set to zero, that is  

In addition, since the energy of the QC determinant is given by the sum of orbital energies, its energy then becomes zero  

By application of the qualitative VB theory, Eq. [41] expresses the HL-bond energy of two electrons in atomic orbitals a and b, which belong to the atomic centers A d B. The binding energy is defined relative to the quasiclassical state ab or to the energy of the separate atoms, which are equal within the approximation scheme. 

It is important to note that these (3 integrals, which we use in the VB 

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SOME SIMPLE FORMULAS FOR ELEMENTARY INTERACTIONS 53 3.5.3 Mixing of Degenerate Valence Bond Structures... 

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