Resonance, among bond structures quantum-mechanical

V. The Quantum-Mechanical Calculation of the Resonance Energy of Benzene and Naphthalene and the Hydrocarbon Free Radicals," J.Chem.Physics 1 (1933) 362374 Linus Pauling and J. Sherman, "The Nature of the Chemical Bond. VI. Calculation from Thermochemical Data of the Energy of Resonance of Molecules Among Several Electronic Structures," J.Chem.Physics 1 (1933) 606617 and Pauling and Sherman, "The Nature of the Chemical Bond. VH. The Calculation of Resonance Energy in Conjugated Systems," J.Chem.Physics 1 (1933) 679686. 

II, plus some additional terms hence, according to the fundamental ideas of quantum mechanics, if it were possible to carry out an experimental test of the electronic structure Oust would identify structure I or structure II, each structure would be found for the molecule to the extent determined by the waee function. The difficulty for benzene and for other molecules showing electronic resonance is to devise an experimental test that could be carried out quickly enough and that would distinguish among the structures under discussion. In benzene the frequency of Kekuld resonance is only a little less than the frequency of the bonding resonance of electron pairs, so that the time required for the experiment is closely limited. 

If we regard each electronic formula as dynamic rather than static, there is little to be gained by emphasizing the concept of resonance hybrids. Furthermore, the detailed theory of resonance has come under heavy fire. It is claimed by A. Burawoy that .. . the interpretation of polyatomic structures does not require the hypothesis of resonance among several idealized valence-bond structures, a speculative application of the quantum-mechanical conception of resonance, which is in disagreement with numerous facts. In view of this controversy, we shall avoid detailed application of the theory of resonance. The theory of molecular orbitals, an alternative treatment, is too complex for the present discussion. 

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