VALENCE-BOND REPRESENTATION FOR THE HYDROGEN-ATOM EXCHANGE-REACTION

With one hybrid atomic orbital per atomic center, the wave function fo r the H + H-2 --> H-2 + H reaction at each stage along the reaction co ordinate may be expressed as a linear combination of the wave function s for eight canonical Lewis structures. For non-negligible orbital ove rlap between the reactants and between the products, the associated gr ound-state resonance is equivalent to resonance between the increased- valence structures (H.H:H) and (H:H.H), for which the two electrons of the (fractional) H:H bonds of these structures occupy Coulson-Fischer -type molecular orbitals. In this paper, these two types of valence bo nd representations, and the associated electronic reorganization and c urve-crossing diagram, are studied via the results of some ab initio v alence bond calculations.