AB-INITIO STUDY OF THE LOWEST 3A' AND 3A'' POTENTIAL-ENERGY SURFACES INVOLVED IN THE O((3)P)+CS(X(1)SIGMA(+))-]CO(X(1)SIGMA(+))+S((3)P) REACTION

Using MCSF and CIPSI-3 methods the shape of the potential energy surface (PES) for the title reaction has been computed for the 3A' and 3A'' states, locating the stationary points on each surface. The results from these two methods show that the wavefunction for all the stationary points has a strong single-reference character and the PES can be well described using the MP4 method. Our results also show that when the dynamical correlation is properly taken into account, the 3A'PES always hes below the 3A''PES. On the 3A'PES we have found three stationary points: the reactants transition state, the OCS minimum and the products transition state. On the other hand, only one stationary point is found on the 3A''PES, the reactants transition state. The geometry of all the stationary points is angular. Finally, the barrier height and the exoergicity computed here agree with the experimental results.