A discussion of the Xα statistical exchange approach for atoms and molecules

The Xα statistical exchange approach has been applied to He + , H, H + 2 and H 2 . The results indicate that, within the Xα method, (1) neither the occupied nor the unoccupied (virtual) orbitals experience a potential due to the remaining ( N −1) electrons; (2) the non-spin-polarized Xα method is not appropriate for open-shell systems; and (3) molecules do not necessarily dissociate to the correct separated atom limit. A comparison is made between these Xα results and the corresponding Hartree—Fock results.