On the calculation of multiplet energies by the hartree-fock-slater method

It is shown that a consistent application of the p ^1/3 approximation of the Hartree-Fock-Slater method requires the use of one specific procedure, the sum method, for the calculation of the energy E _s ¹ of singlet excited states of closed shell molecules. Further, E _s ¹ is found to be in reasonable agreement with experiment for a number of molecules, contrary to the energy E _s ² obtained according to another method discussed in the literature. The calculation of other multiplet splittings than singlet-triplet in the Hartree-Fock-Slater method is also considered.