Development of the four-body corrected fragment molecular orbital (FMO4) method

► The four-body corrected fragment molecular orbital (FMO4) scheme has been implemented. ► This protocol was usable for a nonconventional fragmentation by separating main and side chains of amino acid residues. ► The HIV-1 protease complex with lopinavir was calculated at the FMO4-MP2/6-31G level. ► This job was completed in 1.4 h with 1024 processors of the Earth Simulator.