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Electron propagator calculations with nondiagonal partial fourth‐order self‐energies and unrestricted hartree‐fock reference states
Author(s) -
Ortiz J. V.
Publication year - 2009
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.560360835
Subject(s) - propagator , open shell , diagonal , hartree–fock method , quasiparticle , self energy , physics , gaussian , quantum mechanics , fock space , electron , atomic physics , ionization , order (exchange) , quantum electrodynamics , mathematics , ion , geometry , superconductivity , finance , economics
Abstract The capabilities of a new electron propagator program, adapted for use with Gaussian 88, are described. Partial fourth‐order self‐energies in the diagonal (quasiparticle) approximation for closed‐shell Hartree–Fock reference states are extended as follows. First, diagonal and nondiagonal self‐energy matrices can now be calculated. Second, unrestricted as well as closed‐shell Hartree–Fock reference states can be employed. Full second‐order and third‐order self‐energies are also possible. Computational procedures are described and estimates are given for the number of operations required for the most difficult steps. One‐electron pictures and quasiparticle models for open shell systems are tested in calculations on the ionization energies of Cr − and CrH − 2 .