Vinylidene-acetylene cation isomerization investigated by large scale ab initio calculations.

摘要: The planar isomerization routes of the vinylidene/acetylene cation in lowest electronic states are accurately examined for first time, by using large scale MRCI and CCSDT calculations a complementary way. They compared with similar performed neutral ground state isomerization. An accurate value adiabatic ionization potential vinylidene (11.26 eV) is predicted. state, 1 2A1, follows an almost flat pathway shallow secondary minimum on 2A' energy surface, before suddenly dropping to stable acetylene X 2Piu. It therefore confirmed be completely unstable respect excited cation, 2B1, which also correlates 2Piu along route, has been studied at same level calculation. This 2B1 lying only 0.15 eV above 2A1 exhibits barrier 0.55 explains earlier assignment this symmetry cation. In addition calculations, comprehensive description important steps drawn from very simple model involving monoconfigurational presented. particular, behavior one unique orbital, namely, 5a1 outer molecular shown govern geometry evolution route C2H2+.