A one-electron approximation to domain-averaged Fermi hole analysis

In general, full domain-averaged Fermi hole (DAFH) analysis for correlated wavefunctions requires explicit use of the correlated pair density, but such a quantity is not always readily available. We propose instead a simple one-electron approximation, which we call pseudo-DAFH or pDAFH, and which requires instead only the natural orbitals (and their occupation numbers). From comparisons of the DAFH and pDAFH modes of analysis for the bond dissociation processes in H-2, N-2 and LiH, as well as for the electronic structure of more complex bonding patterns, such as in CH2Li2 and Li-4, we conclude that pDAFH analysis could indeed prove to be very useful when the correlated pair density is not available. Detailed comparisons are also presented of values of the shared-electron distribution index (SEDI), a proposed one-electron approximation to it (pSEDI) and a generalized Wiberg index.