Norbornane: An investigation into its valence electronic structure using electron momentum spectroscopy, and density functional and Green’s function theories

Abstract

We report on the results of an exhaustive study of the valence electronic structure of norbornane (C 7 H 12 ), up to binding energies of 29 eV. Experimental electron momentum spectroscopy and theoretical Green's function and density functional theory approaches were all utilized in this investigation. A stringent comparison between the electron momentum spectroscopy and theoretical orbital momentum distributions found that, among all the tested models, the combination of the Becke-Perdew functional and a polarized valence basis set of triple-quality provides the best representation of the electron momentum distributions for all of the 20 valence orbitals of norbornane. This experimentally validated quantum chemistry model was then used to extract some chemically important properties of norbornane. When these calculated properties are compared to corresponding results from other independent measurements, generally good agreement is found. Green's function calculations with the aid of the third-order algebraic diagrammatic construction scheme indicate that the orbital picture of ionization breaks down at binding energies larger than 22.5 eV. Despite this complication, they enable insights within 0.2 eV accuracy into the available ultraviolet photoemission and newly presented (e,2e) ionization spectra, except for the band associated with the 1a 2 Ϫ1 one-hole state, which is probably subject to rather significant vibronic coupling effects, and a band at ϳ25 eV characterized by a momentum distribution of ''s-type'' symmetry, which Green's function calculations fail to reproduce. We note the vicinity of the vertical double ionization threshold at ϳ26 eV.

High resolution electron momentum spectroscopy of the valence orbitals of water

“…The sets of Feynman-Dyson transition amplitudes ({X fi }) required to expand Dyson orbitals derive [12,63] from the 1h and 1p components of the associated eigenvectors (HX = XE, X X = 1). By virtue of its treatment of static and dynamic self-energies, through fourth-and thirdorder in correlation [54], respectively, the 1p-GF/ADC(3) approach predicts vertical one-electron ionization energies within accuracies of $0.2 eV [64,65]. In contrast with comparable MR-SDCI (multi-reference single and double CI) treatments, the 1p-GF/ADC(3) scheme is size-consistent [66] and applicable therefore to extremely large systems [67].…”

Probing molecular conformations in momentum space: The case of n-pentane

“…The protocol by Ayala and Schlegel 47 also employs an improved analytical approximation, according to a best-fit procedure, of the formula of Pitzer and Gwinn 50 for the partition function associated with one-dimensional hindered internal rotations. The accuracy of the ADC͑3͒/cc-pVDZ calculations of one-electron ionization energies is typically around ϳ0.2 eV for saturated hydrocarbon compounds 56 and further improvements of the basis set have been comparatively shown to have only a very marginal influence on these energies, 57 typically less than 0.1 eV, reflecting the near completeness of the basis set for such systems. All DFT calculations presented in this work have been performed using the GAUSSIAN98 package of programs.…”

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

“…[40][41][42] Further physical phenomena that can strongly influence the recorded momentum distributions pertain to nuclear dynamics. Following Hajgató et al 43 or Deleuze et al, 44,45 it is useful to distinguish nuclear dynamics in the initial and neutral electronic ground state, comprising thermally induced conformational rearrangements [46][47][48][49][50][51][52][53][54][55][56][57][58][59][60] or pseudo-rotational motions, 61,62 from nuclear dynamics in the final ionized state, more specifically, geometrical relaxation, vibronic coupling interactions, and ultra-fast bond cleavages [43][44][45][63][64][65][66][67] induced by the ionization processes of interest.…”