HF Surfaces for A B Interactions

HF Surfaces for A + B Interactions.—There is another general class of diatomic AB systems for which the Hartree-Fock wavefunction for large internuclear separation passes properly into the product of the Hartree-Fock wavefunctions for A and B. This occurs when A possesses a closed shell and B has a half-filled orbital. Again, as Wahl has documented,83 the Hartree-Fock SCF method yields semi-quantitative potential curves for such systems. In the diatomic examples of such systems, no electron pair initially present is broken and no new one is formed, for example, Na(a5) + He(15)toformNaHe(aS+)orHe(1 + F(2P) to form HeF(2II). 

The above results indicate that the Hartree-Fock SCF method is, in general, not a suitable one for calculating the potential surface of a system in which a bonded pair and an unshared electron are exchanged between reactants and products, i.e. reactions of the type 

HF Surfaces for Ss2 Reactions.—We now return to the review of the reactions which have been studied at the single-determinantal SCF level of approximation. The majority of these studies have concentrated on mapping out the minimum energy pathways between reactants and products. Such reaction pathways for a number of Ss2 displacement reactions have been determined. The systems which 

Bunton, Reaction Mechanisms m Organic Chemistry , ed. J. H. Ridd, Elsevier, Amsterdam, 1963, vol. 1. 

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