Study of the photoelectron and electron momentum spectra of cyclopentene using benchmark Dyson orbital theories

Abstract

Abstract:A complete study of the valence electronic structure and related electronic excitation properties of cyclopentene in its C s ground state geometry is presented. Ionization spectra obtained from this compound by means of photoelectron spectroscopy (He I and He II) and Electron Momentum Spectroscopy have been analyzed in details up to electron binding energies of 30 eV using one-particle Green's function (1p-GF) theory along with the outer-valence (OVGF) and the third-order algebraic diagrammatic construction [ADC(3)] schemes. The employed geometries derive from DFT/B3LYP calculations in conjunction with the aug-cc-pVTZ basis set, and closely approach the structures inferred from experiments employing microwave spectroscopy or electron diffraction in the gas phase. The 1p-GF/ADC (3) calculations indicate that the orbital picture of ionization breaks down at binding energies larger 2 than ~17 eV in the inner-valence region, and that the outer-valence 7a′ orbital is also subject to a significant dispersion of the ionization intensity over shake-up states. This study confirms further the rule that OVGF pole strengths smaller than 0.85 foretell a breakdown of the orbital picture of ionization at the ADC(3) level. Spherically averaged (e, 2e) electron momentum distributions at an electron impact energy of 1200 eV that were experimentally inferred from an angular analysis of EMS intensities have been interpreted by comparison with accurate simulations employing ADC(3) Dyson orbitals. Very significant discrepancies were observed with momentum distributions obtained from several outer-valence ionization bands using standard Kohn-Sham orbitals.

Vibrational effects on valence electron momentum distributions of CH2F2

“…The inference is supported by the fact that considerable deviations of experimental momentum profiles from equilibrium geometry calculations have indeed been observed for such orbitals. 21,23,30,56,57 For instance, it has recently been reported by Miao et al that the experimental momentum profiles of the 4b 2 and 1a 2 orbitals of (CH 3 ) 2 O exhibit noticeable intensity near p = 0 whilst the orbitals are not totally symmetric. 30 A similar tendency has also been reported for the 2b 2 orbital of H 2 CO by Brion and his co-workers.…”

Green's function methods for calculating ionization potentials, electron affinities, and excitation energies

“…for small and medium‐sized organic molecules. Recent examples of using GF calculations of one‐electron and shake‐up ionization energies as well as Dyson orbital electron momentum distributions for interpretation of the results of electron momentum spectroscopy may be found in the works of Deleuze and coworkers 62–64. Examples of using semiempirical implementation of GF can be found in the works of Danovich et al40–45…”

Theoretical study of molecular vibrations in electron momentum spectroscopy experiments on furan: An analytical versus a molecular dynamical approach

“…[7][8][9] In the vast majority of cases (see, e.g., Refs. [10][11][12], Kohn-Sham orbitals represent excellent approximations to normalized Dyson orbitals and enable, therefore, quantitative insights into experimental (e,2e) momentum distributions in the high energy limit. a) Author to whom correspondence should be addressed.…”