Characteristics of Precession Electron Diffraction Intensities from Dynamical Simulations

TL;DR

Precession Electron Diffraction (PED) improves crystal structure analysis by reducing intensity oscillations and phase sensitivity, with a new faster simulation method based on scattering matrix data.

Contribution

This study provides a detailed dynamical simulation analysis of PED, revealing its effects on intensity behavior and introducing a novel, faster computational approach.

Findings

PED reduces chaotic intensity oscillations with thickness.

PED shows decreased sensitivity to structure factor phases.

A new faster method for dynamical calculations using scattering matrix data.

Abstract

Precession Electron Diffraction (PED) offers a number of advantages for crystal structure analysis and solving unknown structures using electron diffraction. The current article uses many-beam simulations of PED intensities, in combination with model structures, to arrive at a better understanding of how PED differs from standard unprecessed electron diffraction. It is shown that precession reduces the chaotic oscillatory behavior of electron diffraction intensities as a function of thickness. An additional characteristic of PED which is revealed by simulations is reduced sensitivity to structure factor phases. This is shown to be a general feature of dynami-cal intensities collected under conditions in which patterns with multiple incident beam orienta-tions are averaged together. A new and significantly faster method is demonstrated for dynami-cal calculations of PED intensities, based on using information contained in off-central columns of the scattering matrix.