TRANSITION-STATE FOR THE DISSOCIATION OF TETRAHEDRAL N-4

The Woodward-Hoffmann forbidden dissociation of tetrahedral N4 to 2N2 has been explored at several levels of ab initio molecular orbital theory. In Cs symmetry, both reactants and products belong to the A′ representation but have different orbital occupancy at the restricted Hartree-Fock (RHF) level. The minimum in the seam of crossing between the reactant and product RHF potential energy surfaces provides a qualitative estimate of the transition state. With a multiconfigurational wave function, this becomes an avoided crossing with a true transition state. The barrier to dissociation at our best level of theory is 63 kcal/mol. © 1995 American Institute of Physics.