Approximate Brueckner orbitals and shakeup operators in electron propagator calculations: Applications to F? And OH?

Abstract

Vertical electron detachment energies of F− and OH− have presented difficulties for perturbative electron propagator methods. A recently derived, nondiagonal, renormalized approximation and two additional improvements are studied here. These improvements are replacement of the Hartree–Fock reference determinant by a determinant of approximate Brueckner orbitals generated by a coupled-cluster doubles calculation and retention of correlation terms in the 2hp–2hp block of the superoperator Hamiltonian matrix. Agreement with experiment is significantly better with these methods. When Hartree–Fock orbitals are used, electron detachment energies are underestimated, but approximate Brueckner orbitals lead to overestimates. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 70: 651–658, 1998