Studies in multiconfiguration Dirac-Fock theory. II. The even-parity low-lying spectrum of Ba I

Abstract

For pt.I see ibid., vol.9, no.16, p.2777 (1976). The low-lying even-parity levels of Ba I have been studied by an ab initio relativistic multiconfiguration self-consistent-field Dirac-Fock procedure. Even though the system is close to LS coupling, non-relativistic calculations are found to be inadequate because relativity substantially modifies the valence-orbital charge distribution. Hund's rules for the ordering of term energies were investigated by examining various energy partitions. The fine structure was investigated by using the EAL method which employs one compromise set of orbitals to describe all the levels regardless of their J values.