New approach to the one-particle Green's function for finite Fermi systems

Implementation and use of a direct, partially integral‐driven non‐Dyson propagator method for molecular ionization

“…We shall particularly concentrate hereafter on the third order, ADC(3), approximation, 6,17,18 but most considerations apply equally well to higher order schemes. In ADC(3) four classes of ionic configurations appear: one-hole (1h) and two-hole-one-particle (2h1p) for the N 2 1-electron configurations, one-particle (1p) and two-particle-one-hole (2p1h) for the N 1 1-electron configurations.…”

“…The solution of the Dyson equation can be cast as an Hermitian matrix eigenvalue problem. 6 In practical applications one, of course, uses an approximation of the self-energy and hence of this Hermitian matrix. Various approximation schemes have been proposed over many years to evaluate the self-energy and Green's functions in general (see for example refs.…”

“…Here, one makes use of the Feynman diagrams to represent the perturbation series of the Green's function or propagator under consideration. Among the diagrammatic methods the Algebraic Diagrammatic Construction (ADC) 6,[11][12][13][14] has proven to be of particular success for the treatment of finite electronic systems. This scheme, which provides access to the entire energy range of the valence-shell ionization, reformulates the diagrammatic perturbation expansion for the Green's function in a simple algebraic form, representing infinite partial summations of certain types of Feynman diagrams.…”

Theoretical study of the valence level photoemission spectrum of C2H2 adsorbed on a Ni metal surface

“…We give a brief review of the one-particle Green-function formalism, and particularly of the ADC(n) approach introduced by Schirmer, Cederbaum, and Walter. 31 We consider an N-electron system with a nondegenerate normalized ground state ͉⌿ 0 N ͘ and energy E 0 N . In the case of a molecule a fixed nuclear geometry is assumed and rotation and vibration degrees of freedom are suppressed.…”

“…A general construction scheme, referred to as ADC(n) ͑algebraic diagrammatic construction accurate to the order n͒ of perturbation theory in the residual electron-electron interaction ͑residual beyond the HF approximation͒ has been developed by Schirmer, Cederbaum, and Walter. 31 This scheme is designed to derive systematically infinite partial summations for M ͑ ͒ complete through a finite order of perturbation theory. In the following we present the essential ingredients of the ADC(n) concept and refer for a more comprehensive discussion of this approach to Ref.…”