Figure 1. Workflow for PIEDA calculations and details on each of PIE terms that are computed [22].

The electrostatic component arises from the Coulomb interaction between polarized charge distributions of fragments. The exchange repulsion term is derived from the interaction between fragments situated in close proximity and is always repulsive; it is due to the Pauli repulsion and is related to the overlap of two occupied orbitals. The charge transfer term arises from the interaction between occupied orbitals of a donor and unoccupied orbitals of an acceptor. The dispersion arises as the interaction between instantaneous dipole moments of two fragments. It is hydrophobic (non-polar) in nature and is obtained in PIEDA from the correlation energy of electrons.