title: Near degeneracy effects on the low-lying spectrum of the iron atom.
abstract: The ground state and the LS terms coming from the ground-state configuration, [Ar]-3d(6)4s(2), of the iron atom are studied by carrying out an all electron Variational Monte Carlo calculation. Explicitly correlated trial functions including near degeneracy effects are used. The effect of electronic correlations and the importance of near degeneracy effects are systematically analyzed for the states here considered and compared with the experimental values. Correlations are important to reproduce, even qualitatively, the low-lying spectrum of this atom. A significant quantitative improvement when comparing with the experimental values is achieved when near degeneracy is considered along with dynamic correlations in the variational trial wave function. Finally, the effect of relativity on the results here reported is discussed.
authors.affiliation: Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Buendía
authors.forename: F J
authors.initials: FJ
authors.lastname: Gálvez
authors.forename: P
authors.initials: P
authors.lastname: Maldonado
authors.forename: A
authors.initials: A
authors.lastname: Sarsa