Partitioning Dynamic Electron Correlation Energy: Viewing Møller-Plesset Correlation Energies Through Interacting Quantum Atom (IQA) Energy Partitioning

Here MP2, MP3 and MP4(SDQ) are energy-partitioned for the first time within the Interacting Quantum Atoms (IQA) context, as proof-of-concept for H2, He2 and HF. Energies are decomposed into four primary energy contributions: (i) atomic self-energies, and atomic interaction energies comprising of (ii) Coulomb, (iii) exchange and (iv) dynamic election correlation terms. We generate and partition one- and two-particle density-matrices to obtain all atomic energy components. Correlation energies represent an atomic stabilisation, by proximity to other atoms, as opposed to direct interactions with other nearby atoms. If general, then a new conceptual image of the nature of correlation energy emerges.