| The nonrelativistic ionization potentials and excitation energies of 1s~2nl states (l = s, p, d, n < 9) for the lithium-like ions of Ti~19+ are calculated by using a full core plus correlation method. And the relativistic effects and mass polarization effects are evaluated with the Pauli-Breit operators as the first-order perturbation corrections. In order to obtain the high-precision theoretical results, the contribution from quantum-electrodynamics (QED) correction is also included by using the effective nuclear charge. The fine structures of Is2nl states (l = p, d, n < 9) for the lithium-like ion are determined by computing the expectation values of the spin-orbit and spin-other-orbit interaction operators in the LSJcoupling scheme.Based on the energies and wavefunations of Is2nl excited states (l = s, p, d, n < 9) for lithium-like ions obtained from the FCPC method, the quantum defects for every Rydberg series of these ions are determined with the single channel quantum defect theory, which should be a smooth function of energy and approximated by a weakly varying function of energy. With the quantum defects obtained in this work as input, the term energies for lowly excited states are calculated again by the iteration method .Thus, the accurate predictions make it possible to predict the highly excited energy below the threshold region of these systems and the results should be reasonable and accurate.We extend the FCPC method to calculate the dipole oscillator strengths for the lithium-like ion (n < 9)of Ti19+. In most cases, it can be shown the agreement between the oscillator strengths from the length and velocity forms is up to four or five digits, the acceleration results agree closely with the length and velocity results too. Combined the discreet oscillator strength, calculated accurately using the energies and wavefunations obtained from the FCPC method, with the single channel quantum defect theory, The oscillator strengths for transitions and the oscillator strength density corresponding to the bounding-free transitions from a certain initial state to all the final states of the Rydberg series are obtained. |
