A Kohn–Sham study of the oxirene–ketene potential energy surface

Stationary points on the oxirene–ketene potential energy surface (PES) are determined using Kohn–Sham density functional theory (DFT) with the B3LYP, B97-1, and B97-2 hybrid exchange-correlation energy functionals. B3LYP and B97-1 predict oxirene to be a transition state, which is at variance with large basis set CCSD(T) calculations, which predict a minimum. The B97-2 functional, which was recently shown to provide improved reaction barriers over B3LYP and B97-1 for a series of simple reactions, predicts oxirene to be a minimum. B97-2 relative stationary point energies are closest to the best CCSD(T) values.