Approaches to bifurcating reaction path

The intrinsic reaction path (IRP) often becomes unstable relative to some nontotally symmetric direction orthogonal to the path through a valley–ridge inflection point. We investigate geometric characters of the potential energy surface around the valley–ridge inflection boundary, and propose some ideas to determine a bifurcating reaction path, or to give a two-dimensional potential energy surface which connects bifurcating point and product regions. As a demonstration, bifurcating reaction paths are calculated for the isomerization reaction of methoxy radical (H3CO→H2COH) by the unrestricted Hartree–Fock (UHF) method.