In both methods, the electronic structure of the central molecule is then obtained with a stateaverage complete active space self-consistent field spin-orbit (SA-CASSCF-SO) calculation in OpenMolcas 23.02 (modified to allow up to 50,000 atoms). Here, we consider 18 S = 5/2 states ( 6 H and 6 F terms) for a 9-in-7 active space (4f 9 configuration) using the second-order Douglas-Kroll-Hess relativistic decoupling, the Cholesky "atomic compact" resolution of the identity method for approximating the two-electron integrals, and ANO-RCC basis sets for all atoms (VTZP for Dy, VDZP for the first coordination sphere, and VDZ for all other atoms). These 18 spin-free states are then mixed with SO coupling and the lowest 16