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Electron propagator theory with the ground state correlated by the coupled‐cluster method
Author(s) -
Meissner Leszek,
Bartlett Rodney J.
Publication year - 1993
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560480810
Subject(s) - propagator , hamiltonian (control theory) , coupled cluster , wave function , electron , cluster expansion , ground state , physics , quantum mechanics , ionization , perturbation theory (quantum mechanics) , fock space , electronic correlation , quantum electrodynamics , mathematics , molecule , ion , mathematical optimization
Ground state electron correlation is introduced into the one‐particle propagator via coupled cluster theory. This defines a similarity transformation of the Hamiltonian, which leads to the complete separation of the ionization and electron attachment aspects of the propagator. The latter makes it possible to solve for each property independently. Furthermore, the frequency (or energy) dependence which characterizes propagator theory is eliminated by introducing a wave operator formalism. It is shown that this procedure is equivalent to the summation of certain types of terms in the electron propagator perturbation expansion to infinite order. Finally, the resulting equations are found to be equivalent to those of the Fock‐space coupled‐cluster (or equivalently the equation of motion coupled‐cluster) method, which provides an explicit wave function for each state, demonstrating the connection between these different approaches for the calculation of ionization potentials and electron affinities. Understanding this relationship permits new and powerful approximations to be proposed. © 1993 John Wiley & Sons, Inc.