Orbital interaction theory

A. Rank, Orbital Interaction Theory of Organic Chemistry, Wiley, 1994 T, A. Albright, J. K. Burden and M.-H. Whangbo, Orbital Interactions in Chemistry, Wiley, 1985. 

A. Rauk, Orbital Interaction Theory of Organic Chemistry, Wiley Interscience, New York, 1994. 

I. Fleming, Frontier Orbitals and Organic Chemical Reactions, John Wiley Sons, Inc., New York, 1976. See also A. Rauk, Orbital Interaction Theory of Organic Chemistry, John Wiley Sons, Inc., New York, 1994, pp. 126-141. 

Orbital interaction theory forms a comprehensive model for examining the structures and kinetic and thermodynamic stabilities of molecules. It is not intended to be, nor can it be, a quantitative model. However, it can function effectively in aiding understanding of the fundamental processes in chemistry, and it can be applied in most instances without the use of a computer. The variation known as perturbative molecular orbital (PMO) theory was originally developed from the point of view of weak interactions [4, 5]. However, the interaction of orbitals is more transparently developed, and the relationship to quantitative MO theories is more easily seen by straightforward solution of the Hiickel (independent electron) equations. From this point of view, the theoretical foundations lie in Hartree-Fock theory, described verbally and pictorially in Chapter 2 [57] and more rigorously in Appendix A. 

In the language of perturbation theory, the two orbitals will constitute the unperturbed system, the perturbation is the interaction between them, and the result of the interaction is what we wish to determine. The situation is displayed in Figure 3.1a. The diagram shown in Figure 3.1 b conveys the same information in the standard representations of PMO or orbital interaction theory. The two interacting but unperturbed systems are shown on the left and the right, and the system after the interaction is turned on is displayed between them. Our task is to find out what the system looks like after the interaction. Fet us start with the two unperturbed orbitals and seek the best MOs that can be constructed from them. Thus,... 

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