Hydrogen peroxide geometry optimization

TABLE 3. Energy and optimized geometry for the A and B states of hydrogen peroxide... 

Trioxirane is a cyclic isomer of ozone but whereas trioxirane has six 7f-electrons, ozone has only four. The relative positions of trioxirane and ozone on the O3 potential surface are of some interest and we have therefore carried out additional calculations in which the geometries of both species were optimized with the 4-31G basis set. This basis set gives more reasonable values of the 0—0 distances (1.468 A in hydrogen peroxide compared with the experimental value of 1.475 A, 1.476 A in trioxirane, and 1.255 A in ozone compared with the experimental value of 1.277 A). Using the 4-31G optimized geometries, ozone is calculated to be 18.0 kcal/mol more stable than trioxirane at the 6-31G level. Distortions Dsn -> Cz ) from the 4-3IG optimized structure for trioxirane lead to an increase in (4-3IG) energy, i.e. the cycUc structure is a local potential minimum in the 4-31G surface for O3 under a Czv symmetry constraint. 

---