Li-like ions are widely exist in astrophysical and laboratory plasmas, and their precise atomic parameters (e.g., excitation energies, transition rates) are critical for plasma diagnostics and spectral analysis. In this work, we employ the GRASP2018 package, a widely used program in atomic structure calculations, to systematically compute the energy levels of the lowest 15 levels and the electric dipole (E1), magnetic dipole (M1), and electric quadrupole (E2) transition rates between them for 17 Li-like ions across the isoelectronic sequence (Z=6-51:C³⁺, F⁶⁺, Mg⁹⁺, P¹²⁺, Ar¹⁵⁺, Sc¹⁸⁺, Cr²¹⁺, Co²⁴⁺, Zn²⁷⁺, As³⁰⁺, Kr³³⁺, Y³⁶⁺, Mo³⁹⁺, Rh⁴²⁺, Cd⁴⁵⁺, Sn³⁷⁺, Sb³⁸⁺). The calculations are based on the multi-configuration Dirac-Fock (MCDF) and configuration interaction (CI) method, incorporating high-order relativistic corrections and QED effects such as Breit interaction, self-energy correction and vacuum polarization. With the computational convergence is achieved, the calculated excitation energies and transition rates are compared with the NIST database and previous theoretical results. Owing to rational basis set construction and larger scale of basis set, the current computational results demonstrate evident improvement over those previously obtained using the same MCDF+CI method. Particularly for the two lowest excited states,[1s²2p]_1/2, _3/2, which exhibit slower convergence, the relative difference between current results and the NIST data is reduced by one to two orders of magnitude compared to earlier MCDF+CI calculations. This accuracy even approaches that achieved by S-matrix methods specifically optimized for the ground state and these two lowest excited states. For transition rates, except for certain weak transitions with rates below 10³s^-1, the difference between our calculations and previous theoretical results obtained with the MCDF+CI method is consistently within 1%. Furthermore, our calculations agree with the NIST data within 5% for the majority of transitions. Comparison with NIST and other prior theoretical results reveals evident discrepancies between our calculations and the NIST values for a small part of excitation energies and transition rates. Nevertheless, our results are consistent with other theoretical results for these specific values, suggesting that these particular energy levels and transitions need more detailed theoretical and experimental investigation. This work provides highly accurate data to support experimental diagnostics and theoretical modeling of astrophysical and laboratory plasmas in future research.
Data Availability:The dataset is publicly available via the Science Data Bank repository:https://www.doi.org/10.57760/sciencedb.j00213.00154(During the review phase, the dataset can be accessed via a private link:https://www.scidb.cn/s/UrqUBv).