Electron-propagator calculations on the photoelectron spectrum of ethylene

Abstract

Electron-propagator calculations are performed on the vertical ionization energies of ethylene with a sequence of correlation-consistent basis sets. Two methods are employed: the nondiagonal, renormalized, second-order (NR2) approximation and the third-order, algebraic, diagrammatic construction. The computational efficiency of the NR2 method permits the use of the correlation-consistent, pentuple ζ basis, which contains 402 contracted Gaussian functions. As the size of the basis set grows, NR2 results for outer-valence ionization energies steadily increase; NR2 errors with the largest basis set are less than ∼0.15 eV. Agreement with prominent, inner-valence peaks is also satisfactory and the ratio of two pole strengths corresponding to inner-valence, Ag2 states is in close agreement with observed intensity ratios.

Electron propagator calculations on C60 and C70 photoelectron spectra

“…54,67 Indeed, two IEs were found: ionization from the 5h u was placed at 11.29 eV and ionization from the 9h g level appeared at 11.65 eV. These include ionizations from the 8h g , 5g u , and 2t 2g MOs.…”

Approximate MCSCF optimization for multiconfigurational spin‐tensor electron propagator method (MCSTEP): The vertical ionization potentials of CO, HCN, HNC, H2CO, and O3

“…Because of these features, initial state nondynamical correlation is correctly handled and ionization or electron attachment is always from a state of pure spin symmetry to a state of pure spin symmetry even if the initial state is open shell. This contrasts with the more usual perturbative electron propagator/single particle Green's function approaches 1–26.…”

“…Vertical ionization potentials (IPs) and electron affinities (EAs) can be determined directly by electron propagator methods 1, 2. Traditionally, these methods have been based on a single‐configurational initial state corrected by perturbation theory 3–26. These methods' applications are usually restricted to closed shell atoms and molecules with only dynamical correlation in their initial states, where they have usually provided reliable low‐lying IPs and EAs.…”

“…These methods' applications are usually restricted to closed shell atoms and molecules with only dynamical correlation in their initial states, where they have usually provided reliable low‐lying IPs and EAs. They are not generally reliably applicable to atoms or molecules with open shell initial states or where the initial states have nondynamical correlation 3–26. G. Born had demonstrated that a unitary group reformulation of electron propagator theory could be used to derive the second‐order and 2p‐h Tamm–Dancoff self‐energy approximations for open‐shell applications 27–29.…”

Comparison of electronic decay of valence ionized fluorinated carbanions and their acids

“…In this approach, all 1-hole and 2-hole-1-particle configurations upon a single-determinant HF-ground state are included; this is absolutely necessary when studying the breakdown of the molecular orbital picture and other complex inner-valence phenomena, as can be seen from various applications. [13][14][15][16][17] In this work we study the ionization and doubleionization spectra of fluorinated carbanions and the corre-sponding acids using ADC Green's functions methods. These systems are highly interesting in several different aspects.…”