Potential energy surfaces related to the ion-molecule reaction C+ + H2

The C+ + H2 ion-molecule reaction has been studied by several experimental groups and appears likely to become the focal point of much experimental and theoretical activity. Ab initio self-consistent-field and configuration interaction calculations have accordingly been carried out for this system. A double zeta basis set of contracted Gaussian functions was employed and as many as 648 configurations included. For isosceles triangle configurations (C2V point group) the 2A1, 2B1, and 2B2 potential surfaces were considered, while for linear geometries (C ∞V) the 2Σ+ and 2Π surfaces were studied. For general (Cs) geometry, the lowest 2A′ potential surface was considered. Properties reported include minimum energy paths and energy profiles for the various processes considered. The intuitive correlation diagram of Mahan and Sloane is given qualitative reliability. Pathways to CH2+ complex formation are shown to depend crucially on the Cs potential surface.