Transferable atoms: an intra-atomic perspective through the study of homogeneous oligopeptides

Here we investigate the intra-atomic ( E intra A ) viewpoint through the study of the atoms C α , H α , N, O, and S in a series of ‘mono’-, tri- and penta-peptides. The remaining inter-atomic viewpoint consists of an electrostatic (via multipole moments), exchange and correlation components respectively, of which the electrostatic component has been previously reported.

Together these four energy components, as calculated from the Interacting Quantum Atoms (IQA) partitioning approach, express the foundation of the Quantum Chemical Topological Force Field (QCTFF). In order to have transferability within a force field, smaller sample systems must be calculated and developed as representative of larger target systems. The C α , H α , N, O and S atoms in a tri-peptide are energetically comparable to those in their penta-peptide configurations, within 2.1 kJ/mol in absolute value (1 exception).