1205.2970 (Alex D. Gottlieb et al.)

Strongly separated pairs of core electrons in computed ground states of
small molecules    [PDF]

Alex D. Gottlieb, Rada M. Weishaeupl

We have performed full CI computations of the ground states of the molecules Be, BeH2, Li, LiH, B, and BH and verified that the core electrons constitute "separated electron pairs" in the strong sense of the APSG ansatz. Remarkably, the structure of the separated core pairs is more complex than one might expect, i.e., the core pair does not simply occupy a single spatial orbital. Our method of establishing the presence of separated electron pairs is direct and conclusive. We do not fit a separated pair model; we work with the wavefunction of interest directly. To establish that a given group of spin-orbitals contains a quasi-separated pair of electrons, we verify by direct computation that the quantum state of the electrons that occupy those spin-orbitals is nearly a pure 2-electron state.

View original: http://arxiv.org/abs/1205.2970