MS-STEM-FEM: A parallelized multi-slice fluctuation TEM simulation tool.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Electron Microscopy

Background:

• Atomic configurations in amorphous materials with medium-range order (MRO) are typically studied using fluctuation transmission electron microscopy (FTEM).
• Existing FTEM simulation software lacks crucial experimental parameters, dynamical scattering, and electron wave phase information, limiting simulation accuracy.
• Previous models were often thinner than experimentally measured samples, creating a scale discrepancy.

Purpose of the Study:

• To introduce MS-STEM-FEM, an open-source software package for simulating FTEM experiments.
• To enhance the fidelity of FTEM simulations by incorporating microscope parameters and complex-valued electron wave propagation.
• To validate the software by comparing simulations with experimental results and to analyze the influence of model features on diffraction measurements.

Main Methods:

• Developed MS-STEM-FEM, a software package utilizing multi-slice transmission electron microscopy (TEM) simulation techniques.
• Incorporated microscope parameters, dynamical scattering, and the complex-valued electron wave phase into simulations.
• Compared MS-STEM-FEM simulations with experimental STEM-FEM data for validation.
• Implemented and analyzed statistical diffraction measures to assess model features.
• Performed simulations with variable resolution microscopy and studied parameter convergence.

Main Results:

• MS-STEM-FEM accurately emulates experimental FTEM conditions.
• The variety of crystallite orientations in thicker models was found to be more influential than dynamical scattering.
• Reduced MRO and increased coherence volume in models correlate with decreased FTEM signal intensity.
• The software demonstrates advantageous model scaling and efficient performance scaling.

Conclusions:

• MS-STEM-FEM provides a more realistic simulation environment for FTEM studies of amorphous materials.
• The software facilitates a deeper understanding of atomic configurations and MRO by bridging the gap between simulation and experiment.
• The findings highlight the importance of model thickness and crystallite orientation in FTEM analysis.