Electronic Structure of CH+

Abstract

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, D_e^R, of 3.3 eV. [D_e^R=E(atoms, calculated) — E(molecules, calculated).] A positive lower bound, D_e^LB, of 0.4 eV was found for the ¹Σ⁺ state. [D_e^LB=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.