A note on the orbital energy-splitting of closed-shell systems in the DODS scheme

Investigating the lowering of the total energy and the orbital energy-splittings of electrons with spins α and β, respectively, in the DODS scheme, ab initio calculations have been performed for the formaldehyde molecule. The results obtained by changing the CO distance and the orbital exponents of the C and O atoms indicate that the decrease of the electron density in the CO bond region causes larger orbital energy-splittings and lowering of the energy.