Radiative transition data for open-shell lanthanide ions are essential for large-scale opacity calculations in astrophysical plasmas, yet fully converged configuration-interaction (CI) treatments remain computationally impractical for such systems because of the rapid growth of configuration spaces. Consequently, practical calculations rely on truncated CI models, making it important to identify which correlation contributions dominate transition amplitudes. In the present work, systematically controlled CI calculations for Gd v are performed within the multiconfiguration Dirac-Hartree-Fock framework to investigate the correlation dependence of radiative transition properties. Significant and highly selective variations in transition strengths are observed between single- and double-excitation models, particularly for transitions associated with the $5p\text{−}5d$ and $4f\text{−}5d$ pathways. Through selective inclusion and removal of specific configurations, the $5p^2\to 5d^2$ pair-excitation correlation is identified as the dominant higher-order correlation contribution affecting the redistribution of transition strengths between different CI models. The analysis further shows that higher-order correlation effects primarily modify strongly allowed transition pathways, while the resulting changes propagate to weaker transitions through configuration mixing between different pathways. These results demonstrate that CI-dependent transition behavior in open-shell ions is governed not only by the overall size of the CI expansion, but also by the selective contributions of specific correlation effects, providing guidance for constructing efficient CI expansions in large-scale atomic structure calculations.

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• Atomic spectra
• Electronic transitions
• Oscillator strength
• Rare-earth ions
• Configuration interaction
• Electron-correlation calculations