DENSITY-FUNCTIONAL POTENTIAL-ENERGY HYPERSURFACE AND REACTIVITY INDEXES IN THE ISOMERIZATION OF X3H+ (X = O, S, SE, TE)

Potential-energy hypersurfaces of protonated O-3, S-3, Se-3 and Te-3 s ystems have been investigated using the gradient-corrected density fun ctional approximation. Both the open (C-2v) and cyclic (D-3b) X-3 stru ctures have been considered in the protonation process. Results show t hat the relative stability of the cyclic form with respect to the tran s-open one increases on going from O-3 to Se-3 and reverses for Te-3. The calculated density functional potential-energy surfaces are consis tent with those (for ozone and thiozone) obtained at the ab initio cor related level of theory. The order of stability and reactivity indices has been rationalized on the basis of orbital hardness values along t he reaction paths.