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Are Common Atom Form Factors in HREM-Simulations Accurate Enough for Quantitative Image Matching?

Published online by Cambridge University Press:  02 July 2020

G. Möbus ,
T. Gemming ,
W. Nüchter ,
M. Exner ,
P. Gumbsch ,
A. Weickenmeier ,
M. Wilson  and
M. Rühle
G. Möbus
Affiliation:
Max-Planck-Institut für Metallforschung, Seestr. 92, D-70174Stuttgart, Germany
T. Gemming
Affiliation:
Max-Planck-Institut für Metallforschung, Seestr. 92, D-70174Stuttgart, Germany
W. Nüchter
Affiliation:
Max-Planck-Institut für Metallforschung, Seestr. 92, D-70174Stuttgart, Germany
M. Exner
Affiliation:
Max-Planck-Institut für Metallforschung, Seestr. 92, D-70174Stuttgart, Germany
P. Gumbsch
Affiliation:
Max-Planck-Institut für Metallforschung, Seestr. 92, D-70174Stuttgart, Germany
A. Weickenmeier
Affiliation:
Max-Planck-Institut für Metallforschung, Seestr. 92, D-70174Stuttgart, Germany
M. Wilson
Affiliation:
Max-Planck-Institut für Metallforschung, Seestr. 92, D-70174Stuttgart, Germany
M. Rühle
Affiliation:
Max-Planck-Institut für Metallforschung, Seestr. 92, D-70174Stuttgart, Germany
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Extract

1.Introduction:If digital image matching between an experimental HREM-image and the simulated image fails, one of the suggested reasons is the “inaccuracy of the atomic form factors“ describing the electron scattering in common simulation packages using the free and neutral atom approximation from Hartree-Fock calculations [1]. In detail, three contributions within the usual form factor calculations are mainly missing: (i) the redistribution of charge in ionic crystals, (ii) the accumulation of charge away from atom sites in covalent crystals, (iii) the inclusion of thermal diffuse scattering (TDS) as well as the correlated vibration of atoms beyond the Einstein-approximation within the Debye-Waller factor (DWF) theory. Each of the three effects have been checked separately:

2.Simulations of TDS by Coupling of Molecular Dynamics Time Series to HREM- Multislice Calculations:70 snap shots of a series of structures of NiAl (4.9 × 5.1 × l0nm) are stored from an equilibrated molecular dynamics simulation with vibration amplitudes corresponding to room temperature.

Type
Computational Methods for Microscopy
Information
Microscopy and Microanalysis , Volume 3 , Issue S2: Proceedings: Microscopy & Microanalysis '97, Microscopy Society of America 55th Annual Meeting, Microbeam Analysis Society 31st Annual Meeting, Histochemical Society 48th Annual Meeting, Cleveland, Ohio, August 10-14, 1997 , August 1997 , pp. 1159 - 1160
Copyright
Copyright © Microscopy Society of America 1997

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References

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