A simple and consistent quantum-chemical fragmentation scheme for proteins that includes two-body contributions

29 August 2022, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


The Molecular Fractionation with Conjugate Caps (MFCC) method is a popular fragmentation method for the quantum-chemical treatment of proteins. However, it does not account for interactions between the amino acid fragments, such as intramolecular hydrogen bonding. Here, we present a combination of the MFCC fragmentation scheme with a second-order many-body expansion (MBE) that consistently accounts for all fragment--fragment, fragment--cap, and cap--cap interactions, while retaining the overall simplicity of the MFCC scheme with its chemically meaningful fragments. We show that with the resulting MFCC-MBE(2) scheme, the errors in the total energies of selected proteins can be reduced by up to one order of magnitude.


quantum chemistry
fragmentation methods
many-body expansion


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