We recently explored LASSI model space construction systematically by introducing the LASSI[r,q] formalism. In LASSI[r,q], the integer r tunes the number of electron hops allowed from one fragment to another, thus generating a variety of so-called "rootspaces" (distinct distributions of electrons and spins across the different fragments); and the integer q tunes the number of fragment statelets per fragment per rootspace. On one end, the choice r = 0 and q = 1 recovers the single LASSCF reference wave function; and at the other extreme, r, q → ∞ recovers the CASCI limit. Test calculations showed that magnetic interactions of a triiron oxo-centered complex [Fe III Fe III Fe II (µ 3 -O)-(HCOO) 6 ] and its singly aluminum-substituted variant can be modeled with qualitative accuracy by r = 1, q = 15, corresponding to many orders of magnitude fewer model states than the number of single determinants in the corresponding CASCI or DMRG-CI calculations, reflecting the shortrange nature of static electron correlation.