1UBQ ) and compare the total energies obtained with the fragmentation methods to those from a single-point calculation for the full protein. The resulting errors in the total energy, ∆E = |E full -E MFCC-X |, are summarized in Table . For the H-MFCC method with hydrogen caps, the error amounts to 2,406 kJ/mol, which is reduced to 905 kJ/mol by adding the fragment-fragment two-body correction in the H-MFCC-MBE(2)-ff approach. Even though the interaction between the hydrogen caps and the fragments and among themselves are expected to be small, correcting for these interactions in the H-MFCC-MBE(2) approach further reduces the error to 602 kJ/mol.