Blockwise perturbative corrections in multiconfiguration calculations based on configuration-state-function generators: A revised analysis of the W xxxviii spectrum

A methodology based on configuration-state-function generators (CSFGs) has recently been implemented in the General-Purpose Relativistic Atomic Structure Package (grasp) to reduce the computational load of configuration-interaction (CI) calculations Y. T. Li et al., Comput. Phys. Commun. 283, 108562 (2023). Large CI calculations can be performed if part of the interaction is treated perturbatively. Here, we present enhancements to the perturbative estimates by implementing blockwise methods, where the blocks are given by configuration-state-functions spanned by CSFGs. We compute excitation energies for $4{s}^{2}4{p}^{6}4d, 4{s}^{2}4{p}^{6}4f$, and $4{s}^{2}4{p}^{5}4{d}^{2}$ states in Rb-like ${\mathrm{W}}^{37+}$ and corresponding transition wavelengths and rates to evaluate the methods. The final relative difference between calculated and experimental wavelengths is 0.01%. Thus, the calculations provide highly accurate values for ${\mathrm{W}}^{37+}$ properties useful for a variety of applications, including fusion applications.