Abstract
In this work, we present two different methods for calculation of the atomic structure for atoms and ions. The first one is the Hartree-Fock pseudo-Relativistic method which can be ab initio where we calculate the atomic parameters theoretically by using, for example, the first three programs of the Cowan (CW) atomic structure code: RCN, RCN2, and RCG. We can also use it semi-empirically by using the fourth CW program RCE and fitting the purely theoretical energy levels with experimental data taken for example from the NIST database. The second one is the Thomas-Fermi-Dirac-Amaldi method which can be ab initio where we calculate the atomic parameters theoretically by using, for example, the SUPERSTRUCTURE (SS) or the AUTOSTRUCTURE (AS) atomic structure codes. We can also use it semi-empirically by using the Term Energy Corrections in SS or the Level Energy Corrections in SS or AS atomic structure codes. As an application of using these methods, we calculate energy levels, oscillator strengths, and transition probabilities for the 5p-6s transitions for the Mo II ion using ab initio and semi-empirical methods with the CW and AS atomic structure codes.