Once again, the "reference" Hilbert space (∆N = ∆S = 0) has a statelet index expectation value of zero for both fragments, implying that all but the very first of the model states in the reference rootspace are deadwood. Recalling that q > ⌈x⌉ is necessary in order to observe a fragment statelet expectation value of x and that in the smaller (11,10) active space the LASSI[1,q] prediction of J is converged by q = 5, we note that all observed expectation values in Table are in principle possible with q = 5, except for the Fe II fragment in the ∆N = -1, ∆S = -1 2 Hilbert space. For this Hilbert space, the value of 6.8 requires at least the n = 7 statelet to contribute significantly to the final wave function, indicating that at least q = 8 is required. We therefore investigate the fragment statelets of the Fe II fragment in the ∆N = -1, ∆S = - 2 Hilbert space in more detail in order to determine why convergence of LASSI [1,q](11,20) with respect to q is so slow. Table presents the occupancies of the five 3d orbitals of the Fe II fragment in the reference state as well as in the first five statelets in the ∆N = -1, ∆S = -1 2 Hilbert space from both the LASSI [1,5] (11,10) and LASSI [1,21] (11,20) calculations. Comparing the reference-state occupancies to the charge-transfer occupancies, we can see that in the smaller active space, the electron is preferentially donated from the reference singly-occupied (b -e) orbitals; whereas in the larger active space, the electron is preferentially donated from the doublyoccupied (a) orbital. The state in which the electron is donated from the doubly-occupied orbital is energetically strongly disfavored in the (11,10) active space. The reason for the extremely high energy of the fifth charge-transfer fragment statelet in the (11,10) active space is that the optimized Fe II 3d a orbital in that active space is strongly mixed with, and in fact primarily composed of, the iron 1s orbital, so that that statelet has the character of a core-ionized state (see Listings 4 and 5 as well as Tables and of the SI). This nonphysical Fe II 3d a orbital is obtained because the LASSCF wave function of the Fe II fragment has the character of an ROHF wave function, so that the energy is insensitive to the shape of the doubly-occupied orbital and that orbital is therefore poorly defined. Table : Occupancies of the 5 3d orbitals of the Fe II fragment in the reference state as well as five statelets in which it donates an electron to the Fe III fragment. Weights of those statelets in the five target LASSI eigenstates, and their total energies relative to the energy of the (11,20) LASSCF reference wave function from various LASSI calculations. Orbital labels correspond to those shown in Fig. of the SI. Orbital occupancies which are lower than the reference state by 0.25 or more are bolded, showing the "source" of the electron which is donated to the other fragment as discussed in the text. Occupancies and energies are averaged and weights are summed over all possible spin orientations (e.g., for the charge transfer statelets, m 1 , m 2 = -3 2 , 2; -1 2 , 1; 1 2 , 0; and