Electron Correlation: Nature's Weird and Wonderful Chemical Glue

It can be argued that electron correlation, as a concept, deserves the same prominence in general chemistry molecular orbital theory. We show how it acts Nature's "chemical glue" at both and supramolecular levels. Electron correlation presented course an least somewhat intuitive manner. also propose simple classification of effects based on their length scales size gap (relative to two-electron integrals). In discussion, we DFT shed light wavefunction theory, conversely. discuss two types "honorary valence orbitals", one related small core-valence gaps, other ability empty 3d orbitals 2nd row elements act backbonding acceptors. Finally, why pursuit absolute total energies for own sake becomes sterile exercise, atomization are more realistic "fix point".