Energy natural orbitals

We propose and numerically demonstrate that highly correlated electronic wavefunctions such as those of configuration interaction, the cluster expansion, so on, electron wavepackets superposed thereof can be analyzed in terms one-electron functions, which we call energy natural orbitals (ENOs). As name suggests, ENOs are members broad family defined by Löwdin, they eigenfunctions density operator. One major characteristics is (orbital) energies all summed up exactly equal to total a wavefunction under study. Another outstanding feature population each ENO varies chemical reaction proceeds, keeping constant though. The study has been driven need for new methods analyze extremely complicated nonadiabatic embedded quasi-degenerate excited-state manifolds. Yet, applied scrutinize many other reactions, ranging from ordinary concerted Woodward–Hoffman forbidden reactions. here present properties couple case studies numerical realization, one about mechanism transfer.