On the electronic structure of the X, A, and B states of CaCl

Abstract

State‐averaged multiconfiguration self‐consistent‐field (SA‐MCSCF)/configuration interaction wave functions are used to characterize the near equilibrium electronic structure of the X ²Σ⁺, A ²Π, and B ²Σ⁺ states of CaCl. Spectroscopic constants T_e, ω_e, and R_e were determined and are in reasonable agreement with experiment although the R_e are uniformly long. The dipole moments for the X, A, and B states and the electronic transition moments for the A–X, B–X, and B–A systems were determined at the CI level and are in good agreement with the available experimental data. The three states are described by a Ca⁺²Cl⁻ core plus one electron in a nonbonding calcium centered orbital, which is polarized away from the Cl⁻ ion. The present calculations are in general accord with the polarizable ion model which has been inferred from experimental analyses of these states. However, participation of the calcium 3d orbital in the A ²Π state is surprisingly limited. Calculations in which the chlorine K and L shells are replaced by effective core potentials reproduce the results of the all electron calculations quite well.