Alternate approaches include Pipek-Mezey, which aims to maximize partial charges on each center and Edminston-Ruedenberg, which aims to maximize the self-repulsion of each orbital. Following the work of Riplinger et al. and our prior work , we use Foster-Boys orbitals in all reported computations. The transformed set of active occupied molecular orbitals are known simply as local molecular orbitals (LMOs). In the DLPNO-CCSD algorithm, 59,66 pairs of LMOs are classified as "dipole pairs," "semi-canonical MP2 pairs," "weak pairs," and "strong pairs"; and these are classified based on energy and/or overlap criteria through a series of cascaded pre-screening steps. The reader is referred to the work of Valeev, Neese, and coworkers 59 and our prior work for a more detailed information on the various pair-prescreening procedures. For triples in DLPNO-CCSD(T)/T, triplets (i, j, k) are determined from strong and weak pairs ij, jk, and ik, with the largest number of weak pairs allowed per triplet defined through the parameter TRIPLES MAX WEAK PAIRS (defaults to 2). This makes the number of contributing triplets proportional to system size. For more details on the triplet prescreening procedure performed in DLPNO-CCSD(T)/T, the reader is referred to prior work. For quadruplets, the procedure is similar to triplets, where quadruplets (i, j, k, l) are determined from strong and weak pairs ij, ik, il, jk, jl, and kl. The maximum number of weak pairs allowed per quadruplet is set through the parameter QUADS MAX WEAK PAIRS, (defaults to 3). The corresponding CCSDT doubles amplitudes from these pairs will later be used to form the quadruples natural orbital (QNO) space for quadruplet ijkl.