“…Additional efforts were systematically undertaken to reduce the steep computational scaling of MP2 energies and gradients, thereby enabling their application to larger molecular systems. Therefore, numerous lower-order scaling algorithms were developed, offering accurate approximations for both the SS- and OS-MP2 energy components at a substantially reduced computational expense. ,,− , These methods primarily reduce the scaling order with system size by leveraging the local nature of electronic correlation, employing strategies such as orbital localization, ,,, atomic-level truncation and exploitation of sparsity in matrix elements, ,,,,,, or molecular fragmentation. ,,,,, …”