Influence of nuclear quantum effects on frozen phonon simulations of electron vortex beam HAADF-STEM images

• Published in: Ultramicroscopy Vol. 164; pp. 62 - 69
• Main Authors: Löfgren, André, Zeiger, Paul, Kocevski, Vancho, Rusz, Ján
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.05.2016
• Subjects: Beams (radiation); Electron beams; Electron vortex beams; Frozen phonons; HAADF; Mathematical analysis; Molecular dynamics; Multislice; Nuclear quantum effects; Orbitals; Phonons; STEM; Vibration; Multislice; Electron vortex beams; Frozen phonons; Nuclear quantum effects; HAADF; STEM
• ISSN: 0304-3991; 1879-2723; 1879-2723
• DOI: 10.1016/j.ultramic.2016.01.007

We have evaluated atomic resolution high-angle annular dark field images with ordinary beams and electron vortex beams for thin crystals of bcc iron, explicitly considering the atomic vibrations using molecular dynamics. The shape of the image representing an atomic column depends on the orbital angular momentum, sample thickness and temperature. For electron vortex beams we observe characteristic doughnut-shaped images of atomic columns. It is shown how the thermal diffuse scattering reduces the depth of their central minima, which get further smeared by finite source size effects. In addition, it is shown that in calculations of HAADF-STEM images at low temperatures one has to explicitly consider the nuclear quantum effects (zero point vibrations), otherwise the effect of atomic vibrations is strongly underestimated. •HAADF STEM images calculated for ordinary beams and electron vortex beams.•Temperature, sample thickness, convergence angle and source size broadening effects.•Zero point vibrations included into the molecular dynamics calculations.