Published February 16, 2023 | Version 1.5.0
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Generalised Oscillator Strengths for the simulation of EELS spectra, with a broader coverage of high energy and minor edges

  • 1. Institute of Physics, University of Münster
  • 2. CEOS GmbH

Description

This deposit contains a tabulated set of generalised oscillator strengths, which are required to compute the double differential cross sections for the inelastic scattering of fast electrons by atoms, i.e. for the simulation of EELS spectra.

These tabulated values are calculated self-consistently within the local density approximation using the exchange correlation potential after Perdew [1]. For this a modified version of a program by Hamann is used [2]. Using this atomic potential the wave function of the ejected free electron is calculated, which is normalised by matching it to spherical Bessel and Neumann functions at large distances from the core [3]. The remaining integral constitutes a spherical Bessel transform. Using the convolution theorem this integral is solved with the fast Fourier transformation routine as done in [4]. A further discussion is available along with the code (see below), or more in-depth (but in German)  in the Thesis of L. Segger.

This updated version offered here greatly expands the number of available edges, but is otherwise identical to the earlier version uploaded at https://zenodo.org/record/6599071.

 

The data offered here is in the GOSH file format, a file format developed for the distribution of such datasets. A description of the file format as used here is included in the file `gosh.md`, while an up to date version can be found at:

https://gitlab.com/gguzzina/gosh

The code used to compute the GOS is publicly available, along with a discussion of the approach and methods,  at:

https://github.com/Br0Fi/goscalc

Files

gosh.md

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Additional details

Funding

ESTEEM3 – Enabling Science and Technology through European Electron Microscopy 823717
European Commission

References

  • [1] J. P. Perdew and A. Zunger, Phys. Rev. B 23 (1981), p. 5048
  • [2] D. R. Hamann, Phys. Rev. B 40 (1989), p. 2980
  • [3] M. Frigge, diploma thesis, WWU Münster (2011)
  • [4] J. D. Talman, Comp. Phys. Comm. 180 (2009), p. 332
  • Egerton, R. F. (2009) Electron Energy-Loss Spectroscopy in the TEM. Rep. Prog. Phys., 72 (1), 016502. https://doi.org/10.1088/0034-4885/72/1/016502.
  • Egerton, R. F. (2011) Electron Energy-Loss Spectroscopy in the Electron Microscope; Springer New York
  • Leonhard Segger, Berechnung generalisierter Oszillatorenstärken für die Quantifizierung von EEL-Spektren, Bachelorarbeit, WWU-Münster 2019