The efficiency of the pair-selected multi-level DLPNO-CCSD(T 0 ) depends in particular on the number of orbital pairs which are treated at the highest accuracy. Due to the use of DOS-based orbital-set maps, there are orbital pairs for which a small relative change is estimated, but which are still treated with the highest accuracy if there is any orbital pair contained in the same set of pairs fulfilling the prescreening condition. Consequently, the number of orbital pairs treated with the highest accuracy would decrease if orbital maps, i.e. explicit one-to-one correspondences between orbitals of different structures, would be used instead of orbital-set maps. In this work, we present a scheme to construct such orbital maps as an alternative to the DOS-based orbitalset maps. The essence of this scheme is finding an orbital map that minimizes the change in the orbital localizations according to orbital-wise partial charges, which can be formulated as a linear assignment problem as mentioned above. In contrast to the DOS scheme, the criterion for orbital kinetic energies is omitted. This work is organized as follows: First, the atom mapping algorithm is introduced in Sec. 2.1.