Potential energy surfaces for the C2+H system. Application: Rotational dynamics of C2 on the ground adiabatic and diabatic surfaces

Adiabatic and diabatic potential energy surfaces (PESs) of the ground and the first excited electronic states for the interaction of C2 ( X 1 Σ g + , a 3 Π u ) +H ( 2 S ) system have been computed from the ab initio multi-reference configuration interaction wave functions including Davidson correction (MRCI + Q), using the augmented correlation-consistent valence quadruple-zeta (aug-cc-pVQZ) basis set of Dunning. Mixing angle and coupling potential have been calculated for all selected ab initio geometries. The C2 bond length was fixed at the experimental equilibrium distance r e = 2.348 bohr of C2 ( X 1 Σ g + ) state. Quantum mechanical coupled states rotational dynamics application has been done on the ground adiabatic and diabatic PESs.