All-electron relativistic self-consistent-field calculations for CO and CO +

Abstract

All-electron relativistic self-consistent-field (RSCF) method is extended to treat linear molecules with many open shells where each open shell has different symmetry. The extension is based on the ω—ω coupling scheme and the projection operator technique. All-electron RSCF calculations with Slater-type basis functions have been performed for the CO molecule with a closed-shell (CO, 1Σ +), one open-shell (CO +, 2Σ +), and two open-shell (CO, 3Π and 1Π) configurations. Basis set studies of the RSCF method indicate that the calculations using basis sets of double-zeta quality produce correct trends and reasonable magnitudes of relativistic effects on total and orbital energies, ionization and excitation energies, and π orbital splittings.