Ab initio potential curve for the b ³Σ^- state of CH⁺

An accurate potential energy curve has been obtained for the b 3Σ- state of CH+ by a convergent sequence of multiconfiguration self-consistent field and configuration interaction calculations. Spectroscopic constants derived from the calculated potential curve are in excellent agreement with experimental data. A long range potential barrier of 0.05 eV is predicted which results from charge-quadrupole repulsive interaction. The calculations show that, in an MCSCF+CI approach, it is most appropriate to view the b 3Σ- state of CH + as a ground state C atom perturbed by a proton. © 1983 American Institute of Physics.