Electronic Structure of CH+

Theoretical potential curves for the lowest 1Σ+, 1Π, 3Π, and 3Σ+ states of CH+ are given. Slater-type orbitals were used as a basis for all wavefunctions. The largest wavefunction used was a 37-term valence bond configuration-interaction wavefunction for the 1Σ+ state. The ground state was established to be 1Σ+ with a rationalized binding energy, DeR, of 3.3 eV. [DeR=E(atoms, calculated) — E(molecules, calculated).] A positive lower bound, DeLB, of 0.4 eV was found for the 1Σ+ state. [DeLB=E-(atoms, experimental) — E(molecule, calculated).] Estimates for the spectroscopic constants of the 1Σ+ states are given. A stable 3Π state lying, about 1 eV above the ground state, was found. Douglas and Herzberg and Douglas and Morton both noted the shallowness of the lowest experimental 1Π state potential curve and the anomalous nature of the vibrational level progression of this state. This effect is probably due to the fact that the stability of the lowest 1Π state results from interaction of the C+(2P) + H(2S) curve with the C(1D) + H+ curve.