Breit-Pauli and Dirac-Hartree-Fock energy levels and transition probabilities in neutral argon

Breit-Pauli and Dirac-Hartree-Fock energy levels and transition probabilities in Ar I are reported for energy levels up to and including 3s(2)3p(5)3d(1)P(1)(o). Through the use of a simple core-polarization model, the term composition of these levels was determined. In order to also obtain accurate results for transitions from the ground state, a more extended correlation model was employed. The agreement in the length and velocity gauges of transition data and the accuracy of the predicted transition energy are factors that determine the accuracy of our results which are compared with experimental and other theoretical data when available.