Ab‐initio MRD – CI calculations on a CNO2 decomposition pathway of nitrobenzene

To study molecular decomposition pathways it is necessary to use ab initio multireference determinant–configuration interaction or MCSCF (multiconfiguration SCF) calculations. The MRD–CI (multireference double excitation–configuration interaction technique of Buenker and Peyerimhoff) calculations on the magnified image decomposition pathway of nitrobenzene were carried out using all of the occupied molecular orbitals in the region of the magnified image bond being dissociated, plus all of the virtual orbitals. An effective CI Hamiltonian was used into which were folded the effects of all of the occupied molecular orbitals from which excitations were not allowed. So far we have investigated the lowest 1A1, 3A1, 1A2, 3A2, 1B1, 3B1, 1B2, 3B2 states and are investigating the higher states. Our results show a wealth of structure in the potential energy surfaces for the various electronic states of nitrobenzene as a function of magnified image distance. A number of the states are predissociative and change dominant configuration one or more times along these potential energy surfaces.