AB-INITIO CALCULATIONS OF THE POTENTIAL-ENERGY SURFACES FOR THE UNIMOLECULAR DISSOCIATION REACTION OF ETHYLENE-OXIDE

Ab initio calculations, including electron correlation, were employed to compute the geometries and energies of all stable C2H4O species, as well as four transition states along the potential surfaces connectin g oxirane to the unimolecular dissociation products, The calculations indicate that the primary step in the major reaction observed experime ntally is the Isomerization of oxirane along the ground-state potentia l surface to acetaldehyde, Calculations indicate that the experimental reaction products are derived from unimolecular decomposition on the acetaldehyde S-0 surface (CH4 + CO) or, after intersystem crossing, al ong the lowest triplet state of acetaldehyde (CH3 + HCO). Additional p athways connecting oxirane to a number of less energetically favorable ring-opened or fragmentation products are also presented. (C) 1997 by John Wiley & Sons, Ltd.