Brueckner orbitals, Dyson orbitals, and correlation potentials

one-electron, correlation potentials are closely related to the concepts of Brueckner orbitals and Dyson orbitals. Brueckner orbitals arise from fulfillment of a maximum-overlap condition between a reference, Slater determinant and the many-electron wavefunction. This condition may be used to define an energy-independent, correlation potential for a given state. Dyson orbitals, in contrast, are associated with electron binding energies and are obtained from a pseudoeigenvalue problem with an energy-dependent, correlation potential. The Brueckner doubles (BD)-T1 approximation of the electron propagator employs an approximate Brueckner determinant in its reference state. Dyson orbitals generated with this approximation are expressed in the Brueckner orbital basis. An application of this approximation to the photoelectron spectrum of Al3O3- enables the assignment of peaks to distinct isomers. Dyson orbitals for the lowest electron detachment energies have high overlaps with occupied Brueckner orbitals that diagonalize the corresponding Fock operator. (C) 2004 Wiley Periodicals, Inc.